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Structuring (physical) source and (virtual) solution folders for portability

Copying here those comments of mine at a discussion on the GraphX project:

https://github.com/panthernet/GraphX/issues/21

describing the source code (physical) folder structure and the Visual Studio solution (virtual) folder structure I’ve been using at ClipFlair and other multi-platform projects.

——

looking at the folders/projects/libraries/namespaces naming, I think it would be more appropriate to add the platform at the end of the name, say GraphX.somePart.PCL, GraphX.somePart.UWA (=Universal Windows Application model [aka Win10]) etc. Not sure how easy it will be though for contributors to merge pending changes via GitHub if you do such drastic changes (I’m still struggling with Git myself, prefer Mercurial)

Speaking of moving the platform to the end of the name (e.g. GraphX.Controls.WPF, GraphX.Controls.SL5 etc.), to do it on the folder names (apart from doing at the source code for packages, target assemblies etc.), I think one has to use some Version Control command to "move" (Git should have something like that) the files to the new folder, else other contributors may have issue merging their changes.

Despite the trouble to do it, I think it is better for the long run. Also, all GraphX.SomePart.* subfolders could then be grouped in a GraphX.SomePart folder as subfolders where a Source or Common subfolder would also exists that has all the common code those platform-specific versions of GraphX.SomePart share (via linked files to ..\Common\SomeFile, ..\Common\SomeFolder\SomeFile and ..\Common\SomeOtherFolder\SomeFile etc.)

This is the scheme I’ve been using (and I’m very satisfied with) at http://clipflair.codeplex.com and other projects (e.g. at the AmnesiaOfWho game [http://facebook.com/AmnesiaOfWho] that has separate versions for SL5, WP7 and WP8 and WPF version on the works, plus WRT (WinRT) and UWA [Universal Windows App] too coming in the near future, with all code and most XAML shared via linked files and UserControl[s])

I meant I’d expect GraphX.Common folder with GraphX.Common.PCL in it and GraphX.Common.WP7 etc. versions for example also in that folder since PCL is usually set at WP8 level. This is just an example.

What I’m saying is that the platform name is the last part of the specialization chain, so logically GraphX comes first then say comes Controls then comes WPF, SL5, WP8 etc. in the folder name.

Also would have 3 parent folders Controls, Common and Logic. The last two would just contain the respective .PCL subfolder for now, but I can contribute subfolders for specific platforms too, esp for those the common PCL profile doesn’t cover. Source would be at Controls\Source, Common\Source, Logic\Source and respective platform specific projects (even the pcl projects) would use linked files

aka

GraphX (contains GraphX.sln)

–\Controls
—-\Source
—-\GraphX.Controls.WP7
—-\GraphX.Controls.WP8
—-\GraphX.Controls.SL5 (contains GraphX.Controls.SL5.csproj)
—-\GraphX.Controls.WPF (contains GraphX.Controls.WPF.csproj)
—-\GraphX.Controls.WIN8
—-\GraphX.Controls.UWA
—- … (more platform specific versions)

–\Common
—-\Source
—-\GraphX.Common.PCL
—- … (platform specific versions, esp. those not covered by the settings chosen at the PCL)

–\Logic
—-\Source
—-\GraphX.Logic.PCL
—- … (platform specific versions, esp. those not covered by the settings chosen at the PCL)

The same structure would also be used at examples to cover the potential of porting some of them to more platforms:

–\Examples
—-\SomeExample
——\Source
——\SomeExample.WPF
——\SomeExample.SL5
—-\SomeOtherExample
——\Source
——\SomeOtherExample.WIN8
——\SomeOtherExample.UWA
etc.

Of course common code at each folder is at the Source subfolder of that folder, shared using linked files (e.g. at \Examples\SomeExample\Source) and platform specific code is inside the respective projects (e.g. at \Examples\SomeExample\SomeExample.WPF)

Similarly the GraphX.sln would contain solution folders "Controls", "Common" and "Examples", though it could also contain separate solution (virtual) folders per platform that have each one of them "Controls", "Common" and "Examples" in them. That is the solution’s folder structure is organized per-platform in such a case. This is mostly useful if you want to focus on a specific platform each time when developing. However since the solution folders are virtual, one could even go as far as having two solutions, one with the same structure as the filesystem folders I suggest and one with a per-platform/target structure.

I follow the per-platform virtual solution folders style at ClipFlair.sln in http://clipflair.codeplex.com, while the real folders are structured as I describe above (where each module has its own physical subfolders for the various platforms). In fact some module subfolders there (say Client\ZUI\ColorChooser) contain their own extra solution file when I want to be able to focus just on a certain module. That solution just includes the respective ColorChooser.WPF, ColorChooser.SL5 etc. subprojects from respective subfolders). Such solutions also contain virtual WPF, Silverlight etc. subfolders that has as children apart from the respective platform-specific project (say ColorChooser.WPF) any other platform-specific projects needed (e.g. ….\Helpers\Utils\Utils.WPF\Utils.WPF.csproj etc.) by that module to compile.

Speaking of Xamarin, adding support for that too could follow the same pattern as described above (PCL where possible and platform-specific versions for .XamarinIOS, .XamarinAndroid etc. where needed)

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VB gotcha: when If function isn’t equivalent to an If-Then-Else block

Just got bitten by the following:

Dim takeN As Integer = If(Integer.TryParse(EdTake.Text, takeN), takeN, itemsCount)

I had used that instead of writing in 2 lines:

Dim takeN As Integer

If not Integer.TryParse(EdTake.Text, takeN) then takeN = itemsCount

However, there’s an important difference:

“If” is a function, so its arguments are evaluated at call-time. The “If” signature is:

image

I guess the default is to pass arguments ByVal (by value) and not ByRef (by reference), although I’d expect the signature to specify it explicitly to avoid confusion. When one passes a literal value (say 15) to TruePart or FalsePart it just gets “boxed” into an Object, whereas if one passes an expression (e.g. “takeN+1” or even just “takeN”) it gets evaluated first, then result is boxed and passed as an Object.

So, whereas one might think (esp. if coming from the ALGOL “Call-By-Name” era) the 1st line to be equivalent to:

Dim takeN As Integer

If Integer.TryParse(EdTake.Text, takeN) then takeN = [RESULT OF TRYPARSE] else takeN = itemsCount

in fact it’s equivalent to:

Dim takeN As Integer

If Integer.TryParse(EdTake.Text, takeN) then takeN = [ANY] else takeN = itemsCount

where ANY is whatever the takeN variable one had defined contains.

I thought the VB compiler was warning when using a variable before having assigned a value to it, but it seems in this case it misses to issue a warning. In fact I just tried:

Public ReadOnly Property Take As Integer
   Get
     Dim takeN As Integer
     Return takeN
   End Get

End Property

and it still doesn’t complain. Strange, probably it sets new local variables to 0 by default, but it shouldn’t encourage a programming style that relies on implicit default values – such syntax usually means there’s a mistake in the source code that can lead to a nasty bug.

The moral of the story? Avoid such shorthand expressions and stick to classic keyword-based syntactical structures – after all structured programming had been introduced as an alternative to the many times incomprehensible programs written in functional programming languages (e.g. due to overuse of nested function calls).

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