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

VOX 2.8.24 - Music player that supports...
VOX just sounds better! The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all audio formats you should ever need.... Read more
Dropbox 24.4.17 - Cloud backup and synch...
Dropbox is an application that creates a special Finder folder that automatically syncs online and between your computers. It allows you to both backup files and keep them up-to-date between systems... Read more
OmniPlan Pro 3.7.1 - Professional-grade...
With OmniPlan Pro, you can create logical, manageable project plans with Gantt charts, schedules, summaries, milestones, and critical paths. Break down the tasks needed to make your project a success... Read more
OmniPlan 3.7.1 - Robust project manageme...
With OmniPlan, you can create logical, manageable project plans with Gantt charts, schedules, summaries, milestones, and critical paths. Break down the tasks needed to make your project a success,... Read more
Adium 1.5.10.4 - Popular instant messagi...
Adium is a fast and free instant messaging client which supports AIM, ICQ, Jabber, MSN, Yahoo!, Google Talk, Yahoo! Japan, Bonjour, Gadu-Gadu, Novell Groupwise, SIP/SIMPLE (Text), and Lotus Sametime... Read more
SteerMouse 5.1 - Powerful third-party mo...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
File Juicer 4.57 - $18.00
File Juicer is a drag-and-drop can opener and data archaeologist. Its specialty is to find and extract images, video, audio, or text from files which are hard to open in other ways. In computer... Read more
1Password 6.7 - Powerful password manage...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
CleanMyMac 3.8.1 - $39.95
CleanMyMac makes space for the things you love. Sporting a range of ingenious new features, CleanMyMac lets you safely and intelligently scan and clean your entire system, delete large, unused files... Read more
Monolingual 1.7.8 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. If you use your computer in only one (human) language, you... Read more

Latest Forum Discussions

See All

Olli by Tinrocket (Photography)
Olli by Tinrocket 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Get drawn in with Olli by TinrocketOlli instantly turns your everyday moments into hand-drawn art and animations. • Watch... | Read more »
Penarium (Games)
Penarium 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: | Read more »
Fire Emblem Heroes is way more profitabl...
Profits for Nintendo's mobile game Fire Emblem Heroes are apparently impressive enough to beat out other Nintendo titles likeSuper Mario Run, despite having 10 times fewer downloads. [Read more] | Read more »
Classic series Robot Unicorn Attack 3 no...
The classic Adult Swim browser game, Robot Unicorn Attack, branched off into a series of popular mobile games. Now, the latest entry into the series, Robot Unicorn Attack 3, is available for iOS and Android mobile devices. [Read more] | Read more »
Sudoku Sweeper (Games)
Sudoku Sweeper 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: A minimalist mashup of Minesweeper and Sudoku. Logic puzzle perfection. Every row, column and zone contains a bomb and one of... | Read more »
Under Leaves (Games)
Under Leaves 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Journey into the forest, the jungle or the depths of the deep blue sea. Find chestnuts for the pigs, a caterpillar for the... | Read more »
Ninja Pizza Girl (Games)
Ninja Pizza Girl 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: In the not-so-distant future, rampart traffic congestion has resulted in only one way to deliver pizzas across town in thirty... | Read more »
SCRAP (Games)
SCRAP 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: That day, for no apparent reason, SCRAP decided to wake up and run. He had to, because his activation was a mistake the "Factory" could... | Read more »
The Bunker (Games)
The Bunker 1.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: The critically acclaimed console hit "The Bunker" comes to iOS, The groundbreaking live-action thriller adventure set in a real... | Read more »
Die With Glory (Games)
Die With Glory 1.2.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.2.0 (iTunes) Description: Die with Glory is an epic adventure game where your goal is to die in glorious fashion. You must help Sigurd, a brave old... | Read more »

Price Scanner via MacPrices.net

New System Clock for macOS by B-Eng Now Avail...
Fehraltorf, Switzerland based B-Eng has announced the release and immediate availability of System Clock, the company’s new system monitor and information app developed exclusively for macOS. System... Read more
DEVONtechnologies Celebrates 15th Anniversary...
DEVONtechnologies celebrates its 15th company anniversary with a 30% discount on all its software products from May 1st through 5th, 2017. In spring 2002, DEVONtechnologies opened its website and... Read more
WaterField Designs Invites Customers to Help...
San Francisco based WaterField Designs invites customers and air travelers to participate in developing the next generation in-flight travel case, the Air Porter. Frustrated with limited legroom,... Read more
Save up to $260 with Apple refurbished 12-inc...
Apple has Certified Refurbished 2016 12″ Retina MacBooks available for $200-$260 off MSRP. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The following... Read more
Digital Paper Tablet Offers Distraction Free...
I typically spend 8-10 hours a day gazing at the screens in my laptops and iPad, as tools of my livelihood, I don’t as a rule use electronic devices for pleasure reading. I subscribe to a daily... Read more
“Today at Apple” Bringing New Educational Ses...
Apple has announced plans to launch dozens of new educational sessions next month in all 495 Apple Stores ranging in topics from photo and video to music, coding, art and design, and more. The hands-... Read more
Smart Finance Free Comprehensive Personal Fin...
Moscow-based indie developer, Alexander Survillo has announced the release and immediate availability of Smart Finance: Personal Finance, Budget & Money 1.1.4, an update to his comprehensive... Read more
12-inch 1.1GHz Retina MacBooks on sale for $1...
B&H has 12″ 1.1GHz Retina MacBooks on sale for $100 off MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: - 12″ 1.1GHz Space Gray Retina MacBook: $1199.99 $100 off MSRP - 12... Read more
13-inch 2.7GHz Retina MacBook Pro on sale for...
B&H Photo has the 13″ 2.7GHz Retina MacBook Pro on sale for $130 off MSRP. Shipping is free, and B&H charges NY & NJ tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro (MF839LL/A): $1169 $... Read more
15-inch 2.2GHz Retina MacBook Pros available...
B&H Photo has the 15″ 2.2GHz Retina MacBook Pro available for $200 off MSRP including free shipping plus NY & NJ sales tax only: - 15″ 2.2GHz Retina MacBook Pro (MJLQ2LL/A): $1799.99 $200 off... Read more

Jobs Board

*Apple* Retail - Multiple Positions- Chicago...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Systems Engineer - California Polyte...
Cal Poly, San Luis Obispo Apple Systems Engineer Department: ITS - Customer & Tech Support (134900) College/Division: Academic Affairs Salary Range: Position Read more
*Apple* Mobile Master - Best Buy (United Sta...
**501042BR** **Job Title:** Apple Mobile Master **Location Number:** 000416-East Lansing-Store **Job Description:** **What does a Best Buy Apple Mobile Master Read more
Best Buy *Apple* Computing Master - Best Bu...
**501195BR** **Job Title:** Best Buy Apple Computing Master **Location Number:** 000211-Colorado Blvd-Store **Job Description:** **What does a Best Buy Apple Read more
*Apple* Mac Computer Technician - GeekHampto...
…complex computer issues over the phone and in person? GeekHampton, Long Island's Apple Premium Service Provider, is looking for you! Come work with our crew Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.