[Scons-users] first builder / download

[Philipp Kraus]

On 2012-08-14 23:41:05 +0200, Gary Oberbrunner said:


> On Tue, Aug 14, 2012 at 5:32 PM, Philipp Kraus

> <philipp.kraus at flashpixx.de> wrote:

>> 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

> 

> Using Value nodes is definitely the way to go.  You don't say how

> you're calling it: are you saying something like this:

>   tgt = Download(Value('http://url/file.tar.gz'))

> 

> ?


Yes,
env.Download( Value("http:/url/source.tar.gz") )
or
env.Download( "http:/url/source.tar.gz" )
or
env.Download( source = "http:/url/source.tar.gz" )

on each call the same error

Thx

Phil
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