[Scons-users] first builder / download

[Philipp Kraus]

On 2012-08-14 00:16:04 +0200, Kraus Philipp said:


> Hi,

> 

> I try to create my first own builder for downloading a file. I read the 

> documentation, but I don't find any good explain to do this.

> 

> This is my code

> 

> def url_downloadfile(target, source, env) :

>     target = open( target, "wb" )

>     f = urllib2.urlopen(source)

>     target.write(f.read())

>     target.close()

>     f.close()

>     return target, source

>     

>     

> def url_emitter(target, source, env) :

>     if (target[0] == source[0]) :

>         target[0] = str(source[0]).split("/")[-1]

>     return target, source

> 

> 

> 

> dw = Builder(action = url_downloadfile, emitter = url_emitter, 

> single_source = True )

> env = Environment(BUILDERS = {"Downloader" : dw})

> 

> env.Downloader( "http://myurl/myfile.tar.gz" )

> 

> 

> 

> I know that I can modify the source / target list with the emitter, so 

> I think it is correct

> because the source list (here only on element) is the url, but the 

> target list is here the url

> also, so I must modify the list, so that the last part of my url should 

> be the target (or a target

> is setup manually, so I use this)

> 

> But now I get scons: *** [myfile.tar.gz] Source <url> not found, needed 

> by target `myfile.tar.gz'.

> 

> This is imho correct, because the url is not a file, so Scons does not 

> know anything about the url.

> How can I change this? I think, my input of the command is only a 

> string object and not a FS Entry

> object


I have modified my source to this:

def url_downloadfile(target, source, env) :
    target = open( str(target), "wb" )
    f = urllib2.urlopen( str(source) )
    target.write(f.read())
    target.close()
    f.close()
    return None


def url_emitter(target, source, env) :
    if not(isinstance(source[0], SCons.Node.Python.Value)) :
        raise SCons.Errors.UserError("URL must be a value type, not 
'%s'" % source[0].__class__)

    if target[0] == source[0] :
        target[0] = File( str(source[0]).split("/")[-1] )

    return target, source

env = Environment( BUILDERS = { "Download" : Builder(action = 
url_downloadfile, emitter = url_emitter, prefix = "http", single_source 
= True, target_factory=File, source_factory=Value ) } )

If I run it, I get the message: scons: *** Do not know how to create a 
target from source `http:/url/file.tar.gz'
Why I get this message? The emitter extracts the file of the url and 
change the target

Thanks

Phil