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Subject: Re: [Boost-build] Building a generator binary then using it?
From: Alexander Sack (pisymbol_at_[hidden])
Date: 2008-10-15 09:43:13

On Tue, Oct 14, 2008 at 9:28 PM, Steven Watanabe <watanabesj_at_[hidden]> wrote:
> Alexander Sack wrote:
>> Alright, my main issue is this is a lot of heavy lifting compared to
>> just doing an install rule and then referencing it from some constant
>> PATH which certainly works. Is there a reason why the build
>> destination is not added to the PATH by default when bjam executes the
>> command in a shell?
> I don't think that's enough, as we may (for instance) always want
> to use the release version of a generated tool.

You can specify the PATH then as a constant.

> Here's what is required currently:
> a) create a feature
> b) specify the variable that the feature should be bound to
> c) create the action
> d) specify the executable to use (somehow this needs to
> make it into the requirements for every target using it.)
> The minimum necessary is
> a) specify the variable to stick the exe name in.
> b) write an action
> c) specify the executable
> exe tblgen : tblgen.cpp ;
> set-command tblgen : COMMAND : tblgen ;
> actions tblgen bind COMMAND
> {
> $(COMMAND) $(>) >$(<)
> }
> make : : @tblgen ;
> ----------------------------------------
> Considerations on how to make the above work
> It would be nice if this could somehow be integrated
> with toolset.flags
> toolset.flags tblgen COMMAND : tblgen ;


> However, we would need to be careful to avoid breaking changes/surprises.
> It seems that it would be safest to require such flags to
> be explicitly specified as target references.
> toolset.flags tblgen COMMAND : <target>tblgen ;
> or some such...
> If this is dealt with by adjusting toolset.handle-flag-value, then
> it will be too late to propagate usage-requirements back. But,
> I don't know that usage-requirements ought to be used in this case.
> Also, this will work the same way for generators as for the make rule.
> thoughts?

Most build tools allow for this (I'm thinking for instance Apache maven).

Just on a side note, I'm a little unhappy with the generator/extension
mechanism. Dare I said it but its WAY too complicated to use for
simple tasks (and highly undocumented to boot, yes the basics is there
but what you actually do and how it works is still somewhat mysterious
at times). That's my 2 cents..


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