I’d like to override File.open so that it automatically searches for a
file in a list of include paths. I’m trying to use alias, but I can’t
get it to work. How to I do it, please? My code to date is:
class File
alias :old_open open
def File.open(filename, *args, &block)
begin
File.old_open(filename, *args, &block)
rescue Errno::ENOENT
exception = $!
unless $options[:include_path].nil?
$options[:include_path].each do |path|
begin
return File.old_open([path, filename].join(SEPARATOR),
*args, &block)
rescue Errno::ENOENT
end
end
end
raise exception
end
end
end
I get the error:
File.open(‘xxx’, ‘r’) =>
NoMethodError: undefined method old_open' for File:Class from (irb):7:inopen’
from (irb):23
from (irb):3
Although a bit of re-design will avoid me having to override
File.open, I’d like to know how to do it in case it becomes
unavoidable in the future
Guy has answer, I’ll expand in case you didn’t fully get it, and then
offer an advicelet.
class File
class << File
alias old_open open
end
end
OR
class File
class << self
alias old_open open
end
end
If I were you, I wouldn’t be redefining such an important method, at
least not without damn good reason. I see no reason not to simply add
your own:
class << File
def find_and_open(name, *args, &block) # Want a better name.
path = find_file(name)
File.open(path, *args, &block)
end
def find_file(name)
# ...
end
private :find_file
end
The resulting code looks more elegant anyway, since there is a
separation of concerns.
Gavin
···
On Wednesday, January 29, 2003, 4:22:14 AM, Tom wrote:
Hi –
I’d like to override File.open so that it automatically searches for a
file in a list of include paths. I’m trying to use alias, but I can’t
get it to work. How to I do it, please? My code to date is:
why does this work with barewords vs. symbols/strings?
-a
···
On Wed, 29 Jan 2003, ts wrote:
class << self
alias old_open open
end
–
====================================
Ara Howard
NOAA Forecast Systems Laboratory
Information and Technology Services
Data Systems Group
R/FST 325 Broadway
Boulder, CO 80305-3328
Email: ahoward@fsl.noaa.gov
Phone: 303-497-7238
Fax: 303-497-7259
====================================
I’d like to override File.open so that it automatically searches for a
file in a list of include paths. I’m trying to use alias, but I can’t
get it to work. How to I do it, please? My code to date is:
If I were you, I wouldn’t be redefining such an important method, at
least not without damn good reason. I see no reason not to simply add
your own:
Guy & Gavin, thanks for the answer.
Gavin, I agree that it’s generally a Bad Idea to override important
methods like File.open. The specific behaviour I wanted in this case
was to cause some third-party code to search for files in a number of
directories, without touching the third party code.
I’m writing a LaTeX build system where input files can reside in any
directories listed in the TEXINPUTS environment variable.
Cheers,
Tom
···
On Wednesday, January 29, 2003, 4:22:14 AM, Tom wrote:
Fair enough. When you perfect it, can you post the code so I can add
it to StandardClassExtensions/IO on the Wiki? (Or you can put it
there yourself, of course.)
Cheers,
Gavin
···
On Friday, January 31, 2003, 5:43:08 AM, Tom wrote:
If I were you, I wouldn’t be redefining such an important method, at
least not without damn good reason. I see no reason not to simply add
your own:
Guy & Gavin, thanks for the answer.
Gavin, I agree that it’s generally a Bad Idea to override important
methods like File.open. The specific behaviour I wanted in this case
was to cause some third-party code to search for files in a number of
directories, without touching the third party code.
