Re: [Boost-build] prototyping alternative Boost.Build syntax

Subject: Re: [Boost-build] prototyping alternative Boost.Build syntax
From: Vladimir Prus (vladimir.prus_at_[hidden])
Date: 2016-10-28 13:11:02

Stefan,

On 28-Oct-16 7:55 PM, Stefan Seefeld wrote:
> On 28.10.2016 12:48, Vladimir Prus wrote:
>> Stefan,
>>
>> On 28-Oct-16 7:44 PM, Stefan Seefeld wrote:
>>>>   A target is just represented as a string in Jam and
>>>> Python.  The internal structures used by the back end
>>>> are created on demand.
>>>
>>> That doesn't help me much. If I want to define a new target I surely
>>> need to invoke some `bjam` function (from the bjam module Vladimir just
>>> mentioned) to declare that.
>>
>> Are you sure you want to define a new target? That would bypass all of
>> logic for creating a target that Boost.Build has?
>>
>> I though that what you're after is to prototype how do use Python do
>> define a metatarget, affectively how to replaceS
>>
>>    exe a : a.cpp ;
>>
>> with equivalent Python code. In order to do that, you only need to know
>> Python interface for declaring metatargets, not b2 interface for
>> declaring targets. Am I missing something?
>
> I'm not sure. I have yet to figure out what the right boundary is to
> interface with the build engine.
> So let's assume I want to try both:
>
> * I want to prototype how to write metatargets in Python

Then, you would need to:

- Build b2 with Python support
- Look at 
https://github.com/boostorg/build/blob/develop/src/build/project.py, 
like 150, where it loads Jamfiles.
- Modify that place and/or load_jamfile method to support loading Python
   modules

> * I want to prototype how to write targets (to eventually replace all of
> the above Boost.Build logic by suitable Python code).

Modify 
https://github.com/boostorg/build/blob/develop/src/kernel/bootstrap.py

so that the bootstrap function has:

    bjam_interface = __import__('bjam')

    bjam_interface.define_action("gcc.compile", "g++ -c -o $(<) $(>)")
    bjam_interface.set_update_action("gcc.compile", "a.o", "a.cpp")

Then, you'd go from there.

-- 
Vladimir Prus
https://vladimirprus.com