Exchanging the extension in a filename

Ruby
1

I have a string representing the name of a java file. I would
like to get a new string, where the extension .java has been
replaced by .class.

My approach was to use String#sub:

filename=“abc/x.java”
filename.sub(/java$/,‘class’)

This works fine, but I wonder whether there isn’t a more
elegant way to do it.

Ronald

2

On 8/14/07, Ronald F. [email protected] wrote:

This works fine, but I wonder whether there isn’t a more
elegant way to do it.

sub is pretty elegant.
If you wanted you could do it like File.join(File.dirname(filename),
File.basename(filename, “.java”) + “.class”)

Ronald

3

filename.sub(/java$/,‘class’)

I’d match the point too, not everything that ends with “java” is java
source file: filename.sub(/.java$/, ‘.class’)

This works fine, but I wonder whether there isn’t a more
elegant way to do it.

What is unelegant about that?

mfg, simon … l

4

On Aug 14, 5:05 am, “Ronald F.” [email protected]
wrote:

elegant way to do it.

Ronald

Ronald F. [email protected]
Phone: +49-89-452133-162

filename = “abc/x.java”
==>“abc/x.java”
filename[ /java$/ ] = “class”
==>“class”
filename
==>“abc/x.class”

5

filename = “abc/x.java”
==>“abc/x.java”
filename[ /java$/ ] = “class”
==>“class”
filename
==>“abc/x.class”

Thanks - this is a nice alternative (for the case I actually
want to modify filename). Of course it assumes that I know
that the file ends in .java (but this is true in my case anyway).

Ronald

6

filename.sub(/java$/,‘class’)

I’d match the point too, not everything that ends with “java” is java
source file: filename.sub(/.java$/, ‘.class’)

In general, yes, but in my case I know that the file ends in .java
anyway, so matching the dot is not so important.

This works fine, but I wonder whether there isn’t a more
elegant way to do it.

What is unelegant about that?

Maybe I did too much shell programming before :wink:

On shell level, I would do a

$(dirname $FILENAME)/($basename $FILENAME java)class

so I was thinking whether I might have overlooked some useful method
in the FilePath or File class which would be helpful here.

Thanks for the advice…

Ronald

7

On Aug 16, 12:57 am, “Ronald F.” [email protected]
wrote:

This works fine, but I wonder whether there isn’t a more
so I was thinking whether I might have overlooked some useful method
in the FilePath or File class which would be helpful here.

Thanks for the advice…

Ronald

If what you are looking for is a way to change the extension of some
".java’ files
to have the extension “.class”, you might try Rio (http://
rio.rubyforge.org)

require ‘rio’
rio(‘abc’).rename files(‘*.java’) do |file|
file.extname = ‘.class’
end

If you want to include files in subdirectories of ‘abc’ use:

rio(‘abc’).rename.all.files(‘*.java’) do |file|
file.extname = ‘.class’
end

Hope this helps,

8

Ronald F. wrote:

I have a string representing the name of a java file. I would
like to get a new string, where the extension .java has been
replaced by .class.

[…]

This works fine, but I wonder whether there isn’t a more
elegant way to do it.

If you are really lazy:

require ‘rake’ # NOTE: Not running rake, just using its library.

java_file = “filename.java”
class_file = java_file.ext(“class”)

If you have a bunch of files that need this, you can do:

require ‘rake’

java_files = FileList[‘src/**/*.java’]
class_files = java_files.ext(“class”)

If you need more extensive filename manipulation, check out the
“pathmap” method (available on both FileLists and Strings when using
rake).

–
– Jim W.

9

2007/8/14, William J. [email protected]:

filename[ /java$/ ] = “class”
==>“class”
filename
==>“abc/x.class”

I’d rather include the dot to avoid renaming files called “foo.notjava”

irb(main):001:0> f=“foo/bar.java”
=> “foo/bar.java”
irb(main):002:0> f[/.java$/]=“.class”
=> “.class”
irb(main):003:0> f
=> “foo/bar.class”

Kind regards

robert