[Scons-users] check for build

[Philipp Kraus]

Am 07.06.2013 um 20:28 schrieb Dirk Bächle:


> On 07.06.2013 19:45, Bill Deegan wrote:

>> Sounds like what you really want is a scanner to get the hash from the source for your download builder.

>> Not a change to your emitter..

>> 

> 

> Another approach would be to put the HTTP header text into a ValueNode, and then let the target (downloaded file) depend on it.


Both ideas are nice, but your idea sound a little bit better. My emitter creates the target filename eg
env.Download("a_target_name", "http://..../file.tar"), so the emitter changes the target name into file.tar, the builder create the access for download.

With an option I can use the target name, that is set in the function call or the name can be replaced by the emitter. 

def __emitter( target, source, env ) :
    # check source, read metainformation, create hash value, if hash value is equal to the value in the SCons database, we don't need to build anything

    target[0].prepare()

    if not env.get("URLDOWNLOAD_USEURLFILENAME", False) :
        return target, source

    try :
        url = urlparse.urlparse( str(source[0]) )
    except Exception, e :
        raise SCons.Errors.StopError( e )

    # get source meta information, create a hash value of the information and push it to the SCons database

    return url.path.split("/")[-1], source

target & source are singles types, so I would like to create a structure like a "check for an existing target / source", so how can I replace the #
values with a correct code. 

Thanks

Phil
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