What's new in AVR 12.0 and VS 2013

We bring IBM i RPG assets forward 1© 2014 by ASNA. All rights reserved.

New language features, a new VS, and some interesting DataGate features lurk!

What’s new with ASNA Visual RPG

and DataGate

Presented by Roger Pence


AVR for .NET 12.0 Overview

• AVR for .NET 12.0 works with Visual Studio 2013• Visual Studio 11.2 works with Visual 2012• Formally, this means that anything older than AVR 11.2

and Visual Studio 2012 is not actively supported!• An alternative to spending $$ on upgrading to

Visual Studio 2013• Use the Visual Studio Isolated Shell

http://msdn.microsoft.com/en-us/library/bb685691.aspx




AVR 11.x/AVR 12.0 coexistence• Visual Studio versions 2012 and 2013 can be

installed on the same PC• So can AVR 11.2 and AVR 12.0, but…• After installing AVR 11.0, recompiled AVR 11.2 apps will

need to be deployed against the AVR 12.0 runtimes• If you have substantial 11.2 apps and don’t want to

upgrade your runtimes, consider using a VM• Windows 8 has Hypervisor Virtual Machine built in


Upgrade tips

• AVR 12.0 installs over AVR 11.2, but earlier AVR versions need to be physically removed before installing AVR 12.0• Install Visual Studio 2013 (or the Isolated Shell)

before installing AVR 12.0• Do all Windows updates before installation• AVR for .NET examples are a separate install—don’t

miss them on the


Just one more thing about Visual Studio. If it makes you feel any better…


Visual Studio “14” is right around the corner!


New or overlooked AVR language features

• Conditional expressions• Automatic properties• BegUsing/EndUsing block• Program described memory files


Conditional expressions

• Conditional expressions return one of two values depending on the value of a *Boolean expression• This is sometimes called a ternary operator• Where “ternary” means “composed of three items”• In this case, the three things are a test, a true result and

a false result• Used appropriately, conditional expressions can

make your code easier to understand• Conversely, you can also brew yourself a mess with

conditional expressions if you aren’t careful!


If Status = “X”Tax = 0

ElseTax = ApplyTaxRate(Amount)

EndIf

Tax = (Status = “X”) ? 0 : ApplyTaxRate(Amount)

Conditional expressions distill these five lines

down to this one line



var = (Boolean test) ? True value : False value

The Conditional Expression general syntax is:

Variable to receive results of the conditional expression.





A Boolean test that results in a true or false value.





The value to assign to the variable if the test is true.


What do you think?

•Which would you rather debug? • Five lines or one line?

• Jeff Atwood, at StackOverflow says,

• Conditional expressions provide a way for you to provide a tested assignment quickly and simply• Conditional Expressions, used wisely, add to the

readability of your code.

If you can’t get away with no code, the next best thing is to start with brevity.

http://blog.codinghorror.com/the-best-code-is-no-code-at-all/


DclFld i Type(*Integer4)DdlFld b Type(*Boolean)DclFld b2 Type(*Boolean)

b = *Falseb2 = *False

i = b2 ? 3.0 : b ? 4 : 5.0 * 9

What is the value of i?


First, let’s add parenthesesi = (b2) ? 3.0 : (b) ? 4 : 5.0 * 9



First, let’s add parenthesesi = (b2) ? 3.0 : (b) ? 4 : 5.0 * 9

Then solve the right-most part first…i = (b2) ? 3.0 : (b) ? 4 : 5.0 * 9

Note: conditional expressions are rightassociative—that is the right-most test is evaluated first.



(b) ? 4 : 5.0 * 9

Is b true? Nope. So this part resolvesto 5.0 * 9. Or 45.



Now it’s a little easier to read/i = (b2) ? 3.0 : 45

Is b2 true. Nope. i’s value is 45.



If (b2) i = 3.0

ElseIf (b) i = 4Else i = 45 EndIf

Or (more simply stated?)…


Conditional expressions

• From • Write clearly, don’t be too clever• Write clearly, don’t sacrifice clarity for “efficiency”

• Use conditional expressions where they add clarity, but don’t get carried away!


If you need to assign a true/false value, don’t forget this chestnut:

MyControl.Visible = (TaxStatus = “T”)

No need for an if statement here! The Boolean test resolves to true or false.

A conditional footnote…


Automatic properties

•Most of us have created classes with AVR that need to surface properties. • To do so, you could simply use a public field, but

public fields won’t data bind when using a strongly-typed collection with your class.


Publishing a public field—won’t data bind!DclFld CMCUSTNO Type(*Integer4) Access(*Public)

To do it properly takes a nine lines of code! DclFld _CMCustNo Type( *Packed ) Len( 9,0 ) BegProp CMCustno Type( *Packed ) Len( 9,0 ) Access( *Public ) BegGet LeaveSr _CMCustNo EndGet BegSet _CMCustNo = *PropVal EndSet EndProp Show class

Private backing field

Public property name and type

Getter

Setter


There has to be a better way!


Borrowing from C#

• C# solves this problem with “automatic properties”

public int Customer { get; set; }

• Under the covers, the compiler generates the backing field. • Succinct. Direct. And readable!


Automatic properties in AVRInstead of doing this:

DclFld _CMCustNo Type( *Packed ) Len( 9,0 )

BegProp CMCustno Type( *Packed ) Len( 9,0 ) Access( *Public )

BegGet

LeaveSr _CMCustNo

EndGet

BegSet

_CMCustNo = *PropVal

EndSet

EndProp

The new DclProp operation code lets you do this:

DclProp CMCustNo Type(*Integer4) Access(*Public)

Show class


87% less code!


Publishing a read-only property

DclProp CMCustNo Type(*Integer4) Access(*Public) + SetAccess(*Private)

Automatic properties add the SetAccess and GetAccess keywords, otherwise they use the same keywords as DclFld/BegProp.


Automatic properties

• Let you specify entity-type classes with substantially less code• Use the new SetAccess and GetAccess keywords to

restrict get or set access•Work in all databinding scenarios•Make your classes much easier to read and create


Using iDisposable objects safely• .NET is a garbage-collected language—there is

usually no need for explicit object disposal• For classes that use pure managed this is great• You’ll rarely need to write a class that needs explicit

object disposal—the GC does that work for you• But, any class that uses Win32 APIs under the

covers needs explicit disposal• These are many .NET Framework classes that work with

COM, the file system, or any number of other native services that need explicit displosal


Driven by convention

• The .NET rule is that if a classes offers a Close or a Dispose method, you must call that method before the class goes out of scope.


This fragment redirects an Excel spreadsheet to an HTTP output steam, using the intrinsic MemoryStream object. This code has the potential to be called many times per day in an ongoing Web app. What’s wrong with it?

DclFld WorkBook Type(XLWorkBook) DclFLd MemStream Type(System.IO.MemoryStream) New()

WorkBook = Query.Exec() *As XLWorkBookWorkBook.SaveAs(MemStream)MemStream.WriteTo(context.Response.OutputStream)


I forgot to call the MemoryStream class’s Dispose() method! This causes a resource/memory leak that will ultimately bring a Web site to its knees!

DclFld WorkBook Type(XLWorkBook) DclFLd MemStream Type(System.IO.MemoryStream) New()

WorkBook = Query.Exec() *As XLWorkBookWorkBook.SaveAs(MemStream)MemStream.WriteTo(context.Response.OutputStream)MemStream.Dispose() Whoops!


Again, borrowing from C#

• AVR 12.0 adds the BegUsing/EndUsing block• This construct provides a convenient way to use

iDisposable objects correctly•With BegUsing/EndUsing, you’ll never forget to call

Dispose() again!


BegUsing/EndUsing provides a protective block with which you surround the instance of an iDisposable object.

DclFld WorkBook Type(XLWorkBook)

BegUsing MemStream Type(MemoryStream) + Value(*New MemoryStream()) WorkBook = Query.Exec() *As XLWorkBook WorkBook.SaveAs(MemStream) MemStream.WriteTo(context.Response.OutputStream)EndUsing


BegUsing/EndUsing

• Typically, using BegUsing/EndUsing, you instance the object in place • You can use BegUsing/EndUsing with an existing

instance of an object, but remember this rule:

After the EndUsing state, the object in use is no longer available! • The safest thing to do is use it as presented on the

previous slide.


You don’t need to ever

call this method!

Why? Didn’t I say that’s the

rule?

Why does the DataSet have a dispose method?


The DataSet’s Dispose() method is an artifact of it inheriting from the MarshalByValueComponent.It’s not there because the DataSet needs a dispose method.


Why do men have nipples?

What's new in AVR 12.0 and VS 2013

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