TweetFollow Us on Twitter

September 30 - UDates

UDates

Jesse Feiler, The Philmont Software Mill

Who am I to argue with a cute, curly-haired orphan, but… Annie was wrong. "Tomorrow, tomorrow, I love ya, tomorrow, you're only a day away" she sang (and at the slightest provocation).

To those of us who have worked on systems that are time-sensitive, we know that "tomorrow" is only sometimes a day away. For example:

  • in most businesses, the "tomorrow" of Friday is Monday
  • similarly, the "tomorrow" of December 24 is December 26 (unless a weekend intervenes, or Boxing Day is a holiday, as in England [and in Canada: Ed.]).
  • and, if you are editing a transaction that was entered days ago in order to fix a typo, you may be processing data as of last week, and the system's idea of "tomorrow" is actually a week ago.

The code to handle all of this is not particularly obscure, and many of us have written it-over and over and over again.

From the earliest days on the Mac, we have had very good date and time manipulation routines available in the toolbox. Recently, the Script Manager incorporated some rather nifty text-parsing routines that it combines with new date routines to make everything transparent, whether you are in Japan or Egypt, and whether you are interested in this era or in one distant by several millennia.

I decided that once and for all I would take the toolbox routines and combine them into some MacApp objects that could be used (and overridden) for almost any purpose involving date manipulation. And thus was the UDates unit born.

From a user's point of view, the two most important objects in UDates are the TDateCluster and the TElapsedTimeCluster. Both are descendants of TCluster and are designed to be placed in TDialogViews.

Here's a step-by-step description of their behavior. Note that both are initialized to a "today" date which will be described later. In addition, assume that Saturday and Sunday are weekends, although UDates allows you to specify any weekend days that you want.

TDateCluster

Now, as you might expect, the two boxes at the left are editable. In fact, they belong to a class called TDateEditText which is a descendant of TEditText. TDateEditText objects are basically TEditTexts but with the added functionality that their Validate methods expect the contents to be a date which is parsable by the Script Manager routines. If the date doesn't pass the Script Manager parsing, Validate fails and MacApp restores the previous value. The programmer can thus always assume that there's a valid date in a TDateEditText.

Finally, the TDateCluster provides the information as to whether the date values it returns are the result of user data entry or of clicking on the radio buttons. In some cases, the program is only interested in the start and stop dates shown in the TDateCluster. In other cases, it is important to know whether the user is after this week's data (regardless of date) or the data for 3/12 – 3/16 specifically.

Here's the interface to TDateCluster:

TDateCluster = OBJECT (TCluster)
fDateObj: TDateObj;         {a TDateObj, probably set to today}
fFrom, fTo: TDateEditText;  {private - use GetStartStop}

FUNCTION TDateCluster.GetStartStop(
                                    VAR d1, d2: LongDateTime;
                                    VAR rChoice: IDType): BOOLEAN;
PROCEDURE TDateCluster.IDateCluster(aDate: TDateObj);
PROCEDURE TDateCluster.DoChoice(
                                    origView: TView; 
                                    itsChoice: INTEGER); OVERRIDE;
PROCEDURE TDateCluster.Fields(PROCEDURE DoToField(
                                    fieldName: STR255;
                                    feldAddr: Ptr;
                                    fieldType: INTEGER)); OVERRIDE;
PROCEDURE TDateCluster.Free; OVERRIDE;
END;

Only IDateCluster and GetStartStop are normally used.

TElapsedTimeCluster

The TElapsedTimeCluster consists of three editable fields: two date-time fields, and one field which represents the number of hours between the two date-times. Thus, after posing the TElapsedTimeCluster in the DateSample program, you can enter 1.5 in the elapsed time field… and after any other event in the dialog, the second date-time field will be adjusted. The TElapsedTimeCluster will take whatever two fields are entered and calculate the third.

{IElapsedTimeCluster can handle a 0 for d2 (stop time) and/or duration. If duration is 0, it is calculated. If d2 (stop time) is 0, it is calculated using duration. You might want to do your own error-checking to make sure that you are passing in good values. TElapsedTimeCluster makes sure that all three fields are consistent: change fFrom or fTo, and fDuration is updated. Change fDuration and fTo is changed. (Yes, it could have been coded the other way, but it wasn't. If you want duration to count backwards from fTo and modify fFrom, modify the object.) GetStartStop gives you the start and stop times.}

Here is the interface to TElapsedTimeCluster:

TElapsedTimeCluster = OBJECT (TCluster)

fDateObj:   TDateObj;           {probably today}
fFrom, fTo: TValDateEditText;   {private - use StartStop}
fDuration:  TValEditText;       {private - use GetStartStop}

PROCEDURE TElapsedTimeCluster.Free; OVERRIDE;
FUNCTION TElapsedTimeCluster.GetStartStop( 
                                    VAR  d1,d2:LongDateTime):BOOLEAN;
PROCEDURE TElapsedTimeCluster.IElapsedTimeCluster(
                                    aDate: TDateObj; 
                                    d1,d2: LongDateTime;
                                    duration: comp;
                                    aStyle: TextStyle);
FUNCTION TElapsedTimeCluster.Validate:LONGINT; OVERRIDE;
PROCEDURE TElapsedTimeCluster.Fields(PROCEDUREDoToField(
                                    fieldName:STR255;
                                    fieldAddr: Ptr;
                                    FieldType:INTEGER)); OVERRIDE;
END;

Again, GetStartStop and IElapsedTimeCluster are likely to be the only methods which you'll call directly. Validate is called for you by TDialogView, but nothing prevents you from calling it yourself at some other time.

TDateEditText

In the DateSample program, the Set "today" dialog allows you not only to set the "today," but also to experiment with a TDateEditText field. Typing in "12" sets the date to March 12, 1990, since the Script Manager defaults to current month and current year. The Script Manager will recognize non-standard delimiters and-as shown in a recent Tech Note-its flexibility will allow it in some circumstances to wander off in very peculiar directions. Fortunately, you can check to see how far afield the parser has gone and set your tolerance level as low or as high as you want.

{The IEditText and IRes methods initialize all fields. You may want to subsequently reset fWantDate or fWantTime. Resetting fDidEdit is undefined (polite for "stupid"). fDate is obtainable in alternate formats by calling GetLongDateTime or GetLongDateRec. }

Here's the interface to TDateEditText:

TDateEditText = OBJECT (TEditText)

fWantDate, fWantTime, fDidEdit, fZeroBlank: BOOLEAN;
fDate: LongDateRec; 

PROCEDURE TDateEditText.Fields(PROCEDURE DoToField(
                                 fieldName:STR255;
                                 fieldAddr: Ptr;
                                 FieldType: INTEGER)); OVERRIDE;
FUNCTION TDateEditText.GetLongDateTime(
                             VAR aDate: LongDateTime):BOOLEAN;
FUNCTION TDateEditText.GetLongDateRec(
                             VAR aDateRec: LongDateRec): BOOLEAN;

PROCEDURE TDateEditText.IEditText(
                                 itsSuperView: TView;
                                 itsLocation, itsSize:VPoint;
                                 itsMaxChars: INTEGER);
     OVERRIDE;
PROCEDURE TDateEditText.IRes(
                                 itsDocument: TDocument;
                                 itsSuperView: TView;
                                 VAR itsParams: Ptr); OVERRIDE;
PROCEDURE TDateEditText.SetDate(
                                 aDate: LongDateTime;
                                 reDraw: BOOLEAN);
FUNCTION TDateEditText.Validate: LONGINT; OVERRIDE;

END;

Once again, the methods shown in bold are the ones which you are likely to call directly. Note one point about IEditText: it does NOT set the initial value; you have to call SetDate. It is generally agreed that the IYourObject methods should leave all fields set to some value (e.g., handles to NIL if not actually allocated). In our recent projects we have tended to separate the setting of values from the initialization of the object. Thus, in a project that uses UDates, we have three methods that handle the fields:

  1. InstallADate (location, etc.)
  2. LoadADate (sets values)
  3. UnLoadADate (gets values)

Similar triplets of methods are used for other types of data entry fields. This works very nicely for cases where one view is used to show and update data from various database records.

TDateObj

The third major object in UDates is the TDateObj. It is initialized to a given date and to the weekends and holidays which it should recognize. Thereafter, it can quickly provide yesterday, tomorrow, next week, etc. as needed. In general, one TDateObj is initialized for the application and is not reset during program execution.

The interface for TDateObj is not provided here, since it is fairly lengthy and is provided in the code which follows.

Using UDates

The objects in UDates are designed to be as basic as possible and still provide the needed functionality. They can be customized in two ways. First of all, they can of course be overridden to change their behavior. Secondly, there are parameters which can be set by the program (e.g., do you want both date and time shown in a TDateEditText field?) to modify their behavior. In general, I have assumed that the parameter setting will be fairly constant within an application, and therefore error-checking for parameters is done only in the Debug version. Both Debug and NonDebug versions should catch errors which a user might make in data entry.

In addition, the TDateCluster and TElapsedTimeCluster are views that are editable in ViewEdit to allow a developer to use a specific application's standard fonts and graphic styles. TElapsedTimeCluster is about as sparse as you can get in terms of text, because in those cases where it's been used, we have always modified the resource to incorporate additional text fields.

The code which follows is for UDates itself as well as for DateSample, a small application which uses UDates and to show the results of various commands via messages in the Debug window.

The code is (I hope) fairly clear and well-annotated, so there's no point in going through it in detail. I will, however, mention a few points which may be of interest.

Creating a new, generalized unit

All programmers, and MacApp programmers in particular, have sections of code which they reuse. In my particular repertoire are a FailDBErr routine that I use to trap Inside Out errors, a unit of utility dialogs, and of course UDates itself. In creating these units, I've found a few points to be useful:
  • Do spend a few extra moments to provide Get… and Set… routines for variables of your objects that would normally be visible to the outside world, even if that outside world is you. In TDateEditText, the GetLongDateRec and GetLongDateTime functions were the last changes made. At first it seemed silly to write these functions when the data could easily be found with the field names. The decision to add the functions was NOT made for reasons of ideological purity; it was made because some of the manipulation code was being written several times in my application.

    Whenever code is duplicated, that's a clue that it's in the wrong place and should be moved to a location where it's written once and done with. In UDates, not every variable is accessible to the outside world; providing Get… and Set… methods for all fields of an object is unnecessary (in my humble opinion). What is necessary is to decide which fields and which common transformations of them are likely to be necessary, and to provide those.

  • Don't think you save time by not having a Fields method for every object. Even if the Fields method has nothing but the object's title (bClass), it may well save you from lost time trying to figure out where you are.
  • In creating new units that you plan to reuse, take a moment to think of all possible uses of the unit. For example, we are in the process of creating a generalized numeric entry object-much like TDateEditText. That object must be a descendant of TEditText and not of TNumberText. Why? The fMinimum and fMaximum fields of TNumberText are LongInts. In addition, lots of TNumberText code assumes LongInt values.
  • Don't use standard segment names. Thus you'll find that in UDates, code is placed into $ADateRes and $ADateFields segments. The –sn option in your MAMake file will allow you to remap these segments to $ARes and $ADates if you want to. By keeping your segmentation at least temporarily separate from normal MacApp segmentation, you can easily make adjustments if you blow up a segment with the infamous >32000 error.
  • Add a local debugging option (such as qTraceDate). You'll notice that this option tracks procedure entries, sometimes printing parameters out so that you can see how things are going. Again, by using your own debugging options, you avoid interfering with MacApp and your other debuggers, so that you don't get a slew of UDates debugging messages while you're trying to debug a database problem.
  • Consider adding additional debugging code to your unit. Debugging code turns out to be (in my experience) some of the most reusable code there is. The bLongDateRec and bLongDateTime Fields options are used all through our applications.

Creating the clusters

Normally, one has a choice of creating views either from templates or programmatically. In UDates, the clusters are designed to be created ONLY from templates-and in fact the appropriate ICluster methods are missing. This is deliberate and should be considered as an advertisement for ViewEdit. The TDateCluster contains eight subviews, each of which must be placed, sized, and identified properly in order for the TDateCluster to work. In addition, the six radio buttons must be named with appropriate base names-and no one would consider hard-coding words like "Today" or "Yesterday," so those would have to be stored in a string resource. The code for doing all of this initialization is about 50 lines long. In a case like this, I do not think that template and programmatic creation are equally appropriate: ViewEdit wins hands down in such a case (even with some of its bugs-which I'm sure will be gone shortly).

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

OmniOutliner Pro 4.2 - Pro version of th...
OmniOutliner Pro is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's... Read more
VLC Media Player 2.2.1 - Popular multime...
VLC Media Player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, MP3, OGG, ...) as well as DVDs, VCDs, and various streaming protocols. It... Read more
Nisus Writer Pro 2.1.1 - Multilingual wo...
Nisus Writer Pro is a powerful multilingual word processor, similar to its entry level products, but brings new features such as table of contents, indexing, bookmarks, widow and orphan control,... Read more
Tinderbox 6.2.0 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more
OmniOutliner 4.2 - Organize your ideas,...
OmniOutliner is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's... Read more
Things 2.5.4 - Elegant personal task man...
Things is a task management solution that helps to organize your tasks in an elegant and intuitive way. Things combines powerful features with simplicity through the use of tags and its intelligent... Read more
NeoOffice 2014.10 - Mac-tailored, OpenOf...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
iPhoto Library Manager 4.2 - Manage mult...
iPhoto Library Manager allows you to organize your photos among multiple iPhoto libraries, rather than having to store all of your photos in one giant library. You can browse the photos in all your... Read more
Web Snapper 3.3.8 - Capture entire Web p...
Web Snapper lets you capture Web pages exactly as they appear in your browser. You can send them to a file as images or vector-based, multi-page PDFs. It captures the whole Web page - eliminating the... Read more
TeamViewer 10.0.41404 - Establish remote...
TeamViewer gives you remote control of any computer or Mac over the Internet within seconds, or can be used for online meetings. Find out why more than 200 million users trust TeamViewer! Free for... Read more

Chainsaw Warrior: Lords of the Night has...
It's time to put the Darkness back in its place now that Chainsaw Warrior: Lords of the Night has officially made it to iOS. | Read more »
A World of Ice and Fire Lets You Stalk 2...
George R. R. Martin’s A World of Ice and Fire, by Random House, is a mobile guide to the epic series. The new update gives you the Journeys map feture that will let you track the movements of 25 different characters. But don't worry, you can protect... | Read more »
Gameloft Announces Battle Odyssey, a New...
Battle Odyssey, Gameloft's newest puzzle RPG, is coming to the App Store next week. Set in the world of Pondera, you will need to control the power of the elements to defend the world from evil. You'll be able to entlist over 500 allies to aid you... | Read more »
Fusion - HDR Camera (Photography)
Fusion - HDR Camera 1.0.0 Device: iOS Universal Category: Photography Price: $1.99, Version: 1.0.0 (iTunes) Description: Fusion creates HDR (high dynamic range) photos by capturing different exposures and then combining them into one... | Read more »
Sago Mini Toolbox (Education)
Sago Mini Toolbox 1.1 Device: iOS Universal Category: Education Price: $2.99, Version: 1.1 (iTunes) Description: Come build with the Sago Mini friends! Use a wrench, try a saw, or hammer some nails. From sewing hand puppets to... | Read more »
You Should Probably Grab Hitman GO While...
Hitman GO is a surprisingly cool (yet also incredibly drastic) departure from the Hitman series. It's well worth playing for any puzzle game fans out there, and at the moment you can get your hands - or garrotte if you will - on it for a mere $0.99... | Read more »
IFTTT is Bringing Do Button and Do Note...
IFTTT has announced Do Button and Do Note for the Apple Watch. Do Button lets you make your own personalized button that can connect to things like your Google Drive, control the temperature in your home with Nest Thermostat, or turn the lights on... | Read more »
How Many Days, Hours, and Minutes Are Le...
Countdown, by Yves Tscherry, is now available on the App Store. The app keeps track of countdowns to your favorite things such as someones birthday or days till the New Year. You can display the time in seconds, minutes, hours, days, weeks, months,... | Read more »
The All-New Misfit 2.0 App is Available...
Misfit has just given their app a complete overhaul. Misfit 2.0 now has a brand new interface with a sleek design and is easier to navigate. You'll be able to sync your Misfit device and look up health and fitness information faster than ever before... | Read more »
Halo: Spartan Strike (Games)
Halo: Spartan Strike 1.0 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0 (iTunes) Description: Delve into 30 challenging missions through cities and jungles using a devastating arsenal of weapons, abilities and... | Read more »

Price Scanner via MacPrices.net

TigerText Introduces First Secure Enterprise...
TigerText, a provider of secure, real-time messaging for the enterprise, has announced the launch of TigerText for the Apple Watch. TigerText for the Apple Watch enables users to securely send and... Read more
The Conservation Fund Partners with Apple To...
The Conservation Fund has announced that it will partner with Apple to help protect working forests in the United States. The Apple initiative will conserve more than 36,000 acres of working... Read more
Clearance 13-inch 2.6GHz Retina MacBook Pro a...
B&H Photo has clearance 2014 13″ 2.6GHz/128GB Retina MacBook Pros now available for $1099, or $200 off original MSRP. Shipping is free, and B&H charges NY sales tax only. Read more
Apple refurbished 2014 13-inch Retina MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ Retina MacBook Pros available for up to $400 off original MSRP, starting at $979. An Apple one-year warranty is included with each model, and... Read more
iMacs on sale for up to $205 off MSRP, NY tax...
B&H Photo has 21″ and 27″ iMacs on sale for up to $205 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1019 $80 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more
Sale! 16GB iPhone 5S for $1 with service
Best Buy is offering 16GB iPhone 5Ss for $1.00 with 2-year activation at a participating cellular provider. Choose free home shipping and activation, or buy online and activate during in-store pickup... Read more
Apple refurbished 2014 MacBook Airs available...
The Apple Store has Apple Certified Refurbished 2014 MacBook Airs available starting at $679. An Apple one-year warranty is included with each MacBook, and shipping is free. These are currently the... Read more
27-inch 3.5GHz 5K iMac on sale for $2349, sav...
 Adorama has the 27″ 3.5GHz 5K iMac in stock today and on sale for $2349 including free shipping plus NY & NJ sales tax only. Their price is $150 off MSRP. For a limited time, Adorama will... Read more
Save up to $380 on an iMac with Apple refurbi...
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $2119 $... Read more
iFixIt Teardown Awards 12-IInch Retina MacBoo...
iFixIt has posted its illustrated teardown of the new 12-inch MacBook Retina. They note that this new MacBook is less than half the thickness of the last Apple notebook called just “MacBook” back in... Read more

Jobs Board

*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Watch SW Application Project Manager...
**Job Summary** The Apple Watch software team is looking for an Application Engineering Project Manager to work on new projects for Apple . The successful candidate Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.