DMD 1.038 and 2.022 releases

[John Reimer]

Hello Yigal,

> Nick Sabalausky wrote:
> 
>> "John Reimer"<terminal.node at gmail.com>  wrote in message
>> news:28b70f8cfcfe8cb30c0a0e2ac70 at news.digitalmars.com...
>> 
>>> Hello Sean,
>>> 
>>>> bearophile wrote:
>>>> 
>>>>> Walter Bright:
>>>>> 
>>>>>> Excess isn't the problem, I want to see if import cycles is.
>>>>>> 
>>>>> Generally all the modules in my dlibs import each other. This is
>>>>> nearly unavoidable, if a module contains string functions, and
>>>>> another one contains math stuff, the string module will want to
>>>>> use some math stuff and the math module may need string
>>>>> representations and processing. In the D specs I haven't seen an
>>>>> advice to not use cyclic imports, so I don't want such compiler
>>>>> flag, I prefer a compiler able to manage such cyclic imports
>>>>> efficiently.
>>>>> 
>>>> Cyclic imports are a bad idea in general because of the impact they
>>>> have on verifiability (unit testing).  But as you say, sometimes
>>>> they're unavoidable.
>>>> 
>>>> Sean
>>>> 
>>> I'd going to wager that they are /often/ unavoidable, especially in
>>> ported projects from other languages that have either no concept or
>>> a different concept of modules/packages.
>>> 
>>> DWT is perhaps the single worse example of cyclic imports.  I'm not
>>> sure
>>> how the design could have been improved in Java's SWT.  All it takes
>>> is
>>> the need to reference one symbol in each module (because each object
>>> apparently needs to just "know" about the other) to create a cyclic
>>> import
>>> issue in D.
>>> Static initialization has also been a problem in DWT such that a few
>>> significant workarounds were necessary.
>>> I agree that the interdepencies should be avoided in all new
>>> projects designed specifically for D.  I'm just not sure what the
>>> solution would be for the great mass of ported software.
>>> 
>>> -JJR
>>> 
>> This might be a naive idea, and wouldn't solve the problems with
>> cyclic dependancies in the general case: But regarding the static
>> initializaton issue (which I've come up against myself), what if
>> static initializers allowed some sort of clause like this:
>> 
>> module foo;
>> import bar;
>> // Exact syntax not really important right now
>> this() dependsOn(bar) {
>> // Do some initing that depends on
>> // bar's static initializer having been run.
>> }
>> That would force foo's static initialization to be run sometime after
>> bar's. Obviously, any cycles in the graph of "dependsOn"s would be an
>> error.
>> 
> I'm curios - why isn't this a problem in other languages like Java
> (and
> I assume .net languages as well)?
> What's different in D that makes this so dificult? the static
> initializers? How is this handled in other languages?


For package scope, ie classes in the same directory, Java does /not/ seem 
to need an import statement, so somehow that suggests cyclic imports do not 
occur as they do in D for name resolution (in the specific case of package 
imports).  But I don't know what happens under the hood: does the fact that 
Java sees the whole package for symbol resolution imply that it reads in 
all symbols initially for a package during compilation?  If so, this would 
almost be equivalent to D, at compile time, reading all package modules as 
if they were one file somewhat similarly to what Derek was suggesting in 
another post.

This is too much speculation from me, though. :)

-JJR