Re: [Boost-build] [Boost][Build][v2] Adding command line options

From: K. Noel Belcourt (kbelco_at_[hidden])
Date: 2006-09-09 00:54:22

On Sep 8, 2006, at 10:42 PM, Rene Rivera wrote:

> K. Noel Belcourt wrote:
>> I want to initialize a constant using a command line value if one is
>> supplied by the user or with some default of my choosing if no
>> argument is supplied.  Something like this though clearly this is
>> illegal since you can't change a constant.
>>
>> constant sierra-root = [ MATCH "^--sierradir=(.*)" : $(argv) ] ;
>> sierra-root ?= /sierra/Release ;
>>
>> So how can I initialize a constant in one step, either with a value
>> from the command line or with some specified default value.
>
> You can't do it in one assignment if that's your question.
Yup, that was the question.

> What you
> have, except for the "constant", seems fine to me. Is there some  
> reason
> you need to do it in one assignment?
Make clear to our other, less knowledgeable BBv2, users that they  
shouldn't mess with this value.  Strongly typed, clear to the casual  
reader, the standard spiel.  I know the value should never be changed  
but other users won't and once I release this build system for  
general use, someone will assume it's mutable, mutate it's value and  
hose the build system.

Not critical, just desirable from a maintenance perspective.

-- Noel