Getting the best out of the IDE when using Modules

Since the last beta version (5.20 beta8) the IDE finally has support for Modules as well (AutoComplete, QuickHelp, ProcedureBrowser etc). Please test these features well, as it was quite a change in the IDE to implement this. Now, to get the best experience when using the IDE and Modules together, there are some simple rules that have to be followed. I will explain them below. But first, let me explain why these limitations exist.

As the AutoComplete feature became smarter and more helpful in past versions, it had to grow from a simple scanning of the source for strings into a full grown analysis of the source code. This is especially required for modules, because the IDE needs to know what procedures/constants/structures are exposed from each module in order to present the correct choices in AutoComplete. So the IDE in essence needs to understand your code. The best way to fully understand code is to compile it. The IDE does not actually compile the code for the following reasons:

  • Speed: The AutoComplete feature cannot introduce delays because that would make it unusable. So compiling the entire code from beginning to end is not an option.
  • The code is usually not compilable anyway: Remember, the purpose of the IDE is to edit code. While you edit a line, it will be in a state that cannot be compiled most of the time. In fact, if you look at all characters typed in a source code, the instances in which that typed character puts the source in a compilable state are rather rare compared to those that put it in a state with errors (from a compiler perspective).
  • There are IDEs that actually have a builtin compiler that can tolerate this and still compile the code. Eclipse is such an example. However, writing something like that is quite complex and is actually harder for PB because of features such as macros and compiler directives.

Instead, the IDE tries its best to (quickly) understand the code without a full compilation. For that, it parses the code and extracts all information that can be understood without context (from a single line of code) into an indexed form for fast search. This organization has the benefit that if a line of code is changed, only this line needs to be parsed again and not the rest of the code which is quite fast. Then when the type of a variable is needed or something like that, the IDE searches through this indexed data to put it in the proper context to answer the question. So it is not a full compilation, but rather a “fuzzy” analysis of the code. In essence, the IDE collects the information it can understand, and stuff that only a compiler would know (like what an expanded macro would look like) is ignored.

So how does this affect Modules? One thing that the IDE does not do is resolve which source file is included where in the final program. It only looks at each source file individually. This was no big limitation before modules existed, but with modules it means you have to follow some rules so the IDE understands where a module begins and ends and what it contains.

These are the rules:

  1. The entire DeclareModule/EndDeclareModule block should be in the same source file.
  2. The entire Module/EndModule is best also written in a single file, but it does not have to be the same one as the one that contains the DeclareModule
  3. At least the file containing the DeclareModule block should be included in the Project and scanned for AutoComplete. You don’t have to include the actual module implementation since the stuff in there is not visible on the outside anyway.
  4. If you use UseModule, all modules that are open within a source file should be opened within that source file. The best was is simply to have the UseModule calls right at the top.
  5. Don’t hide the essential module commands behind macros. The IDE does not expand macros so it will not know that the keywords are in there.

The explanation is rather simple. Consider this code:

DeclareModule Foo
  XIncludeFile "FooDeclaration.pb"

Since the IDE only looks at each source file individually, it does not know that the contents of FooDeclaration.pb are part of the module declaration. So the IDE sees an empty Foo module, plus a file FooDeclaration.pb with stuff that is outside of any module.

In the same way, if you have a UseModule call outside of the current source file, the IDE does not know that stuff from the opened module is available while you edit your file and therefore cannot help you with AutoComplete in this case.

Other languages enforce such rules on the compiler level (one class per file etc). We chose to not limit the compiler in this way so you can organize your code as you like. And you don’t have to follow these rules to use the IDE. It just cannot be as helpful as it could be if you don’t. Anyway, in my opinion these rules also make sense from a code organization standpoint so i don’t think it is that hard to follow them.


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