Why can't an `Import[]` change $Path?

Question

Does anyone know why Import["http://**server**/file.m"] can't make a change to $Path? It seems like file.m can set pretty much any other variable, but not $Path.

I suspect Get[] would work, but I can't seem to get Get[] to fetch files over the web.

Answer 1

I think \$Path is probably being set in a Block in the Import call. I put this sample code on a server in test.m:

beforePath = $Path;
    AppendTo[$Path, "d:/tomcat-6.0.35"];
afterPath = $Path;
DateString[]

I can see that afterPath has the correct value, but $Path is unmodified.

In[14]:= Import["http://jfkleinlx.wri.wolfram.com/test.m"]

Out[14]= "Thu 17 Jan 2013 09:58:52"

In[19]:= Complement[afterPath, beforePath]

Out[19]= {"d:/tomcat-6.0.35"}

In[20]:= $Path === beforePath

Out[20]= True

With V9, to work around this you can open a stream to a URL and use Get as you suspected:

In[21]:= st = OpenRead["http://jfkleinlx.wri.wolfram.com/test.m"]

Out[21]= InputStream["http://jfkleinlx.wri.wolfram.com/test.m", 133]

In[22]:= Get[st]

Out[22]= "Thu 17 Jan 2013 10:06:11"

In[24]:= $Path === afterPath

Out[24]= True

Remember to Close the stream. Or, you can just Get the URL directly: Get["http://jfkleinlx.wri.wolfram.com/test.m"], which opens a stream internally.