[Scons-users] first builder / download

[Dirk Bächle]

Hi Phil,

On 17.08.2012 07:42, Philipp Kraus wrote:

>

>

> For example I try to download the newest version of the LUA sources, 

> so I create a function for parsing the HTML page source

>

> def LUA_DownloadURL()  :

>    # read download path of the LUA library (latest version)

>    f = urllib2.urlopen("http://www.lua.org/download.html")

>    html = f.read()

>    f.close()

>

>    found = re.search("<a href=\"ftp/lua-(.*)\.tar\.gz\">", html, 

> re.IGNORECASE)

>    if found == None :

>        raise RuntimeError("LUA Download URL not found")

>

>    downloadurl = found.group(0)

>

>    downloadurl = downloadurl.replace("\"", "")

>    downloadurl = downloadurl.replace("<", "")

>    downloadurl = downloadurl.replace(">", "")

>    downloadurl = re.sub(r'(?i)a href=', "", downloadurl)

>    downloadurl = "http://www.lua.org/" + downloadurl

>

>    filename    = downloadurl.split("/")[-1]

>

>    return downloadurl, filename

>

> The function must return first the URL of the download and on second 

> the target filename, the main scons script shows:

>

> x = env.ParseAndDownload( LUA_DownloadURL )

>

> and in x is the target filename stored (actually lua-5.2.1.tar.gz)

>

> Can you send me some tips to create better code?

>

> Thanks

>

> Phil

>

>

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>


in total, wouldn't it be easier to simply check whether the target file 
from your download exists with Python?
Something like:

   url, target = LUA_DownloadURL()
   if not os.path.isfile(target):
     # Download file here

I fail to see what you are winning when you try to use SCons constructs 
for the download. Having the file "to download" 
(http://www.lua.org/whatever) connected to the dependency graph would 
mean that SCons has to download the file each and every time the user 
starts a build. Just to check whether the file changed, 
accidentally...you never know, better make sure.
Is this really what you want to happen in the end?

Oh, and thanks a lot for "finally" telling us what you really intend to 
do with all that code of yours. ;)

Best regards,

Dirk