# Warning message about "initialized constant" **URL:** \ **Category:** Ruby\ **Created:** [June 23, 2006, 4:54pm UTC](https://www.ruby-forum.com/t/warning-message-about-initialized-constant/64258 "2006-06-23T16:54:55Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\ **Post date:** [June 23, 2006, 4:54pm UTC](https://www.ruby-forum.com/t/warning-message-about-initialized-constant/64258/1 "2006-06-23T16:54:55Z")
This is part of a script I use that simply ftps a bunch of files over to a UNIX server at my company. It does work, but, I keep getting a warning message from RUBY about “rb:20:warning: already initialized constant BWDFile”. The line 20 it’s referring to is my line 5 below. ## Thanks for any help. … 1 ftp = Net::FTP.open(‘[quark.bna.com](http://quark.bna.com)’) do |ftp| 2 ftp.login(‘xxxxxx’,‘xxxxxxxx’) 3 ftp.chdir(‘/xxxxx/xxx/xxd/xxxx’) 4 BWDFiles=Dir.glob(“\*.{pdf,gif}”) 5 BWDFiles.each do |BWDFile| 6 ftp.putbinaryfile(BWDFile) 7 FileUtils.rm(BWDFile) 8 end 9 end ---
**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\ **Post date:** [June 23, 2006, 5:06pm UTC](https://www.ruby-forum.com/t/warning-message-about-initialized-constant/64258/2 "2006-06-23T17:06:21Z")
Peter B. wrote: > This is part of a script I use that simply ftps a bunch of files over to > a UNIX server at my company. It does work, but, I keep getting a warning > message from RUBY about “rb:20:warning: already initialized constant > BWDFile”. The line 20 it’s referring to is my line 5 below. [snip] In Ruby, identifiers starting with uppercase are constants. Constants, different from variables, are not supposed to change. Thus the warning, because you try to use a variable as a constant Additionally, camelCase is usually reserved for class names (as a convention), it’s considered better style to use snake\_case, in your case you are better off using “bwd\_file” as the variable name. t. ---
**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\ **Post date:** [June 23, 2006, 5:06pm UTC](https://www.ruby-forum.com/t/warning-message-about-initialized-constant/64258/3 "2006-06-23T17:06:31Z")
On Jun 23, 2006, at 9:55 AM, Peter B. wrote: > … > 1 ftp = Net::FTP.open(‘[quark.bna.com](http://quark.bna.com)’) do |ftp| > 2 ftp.login(‘xxxxxx’,‘xxxxxxxx’) > 3 ftp.chdir(‘/xxxxx/xxx/xxd/xxxx’) > > 4 BWDFiles=Dir.glob(“\*.{pdf,gif}”) > 5 BWDFiles.each do |BWDFile| > 6 ftp.putbinaryfile(BWDFile) > 7 FileUtils.rm(BWDFile) > 8 end > 9 end One of the conventions of the Ruby language is that capitalized variable names are considered constants. You can fix your problem by changing BWDFiles to bwd\_files and BWDFile (which changes each iteration therefore it isn’t constant) to bwd\_file. Ruby only CamelCases class names, never variables. If you stick with the conventions, other rubyists reading your code will have an easier time deciphering it. > 4 bwd\_files=Dir.glob(“\*.{pdf,gif}”) > 5 bwd\_files.each do |bwd\_file| > 6 ftp.putbinaryfile(bwd\_file) > 7 FileUtils.rm(bwd\_file) > 8 end > 9 end cr ---
**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\ **Post date:** [June 23, 2006, 5:09pm UTC](https://www.ruby-forum.com/t/warning-message-about-initialized-constant/64258/4 "2006-06-23T17:09:42Z")
Anton ‘tony’ Bangratz wrote: I hate replying to myself. But yikes: [snip] > In Ruby, identifiers starting with uppercase are constants. Constants, > different from variables, are not supposed to change. Thus the > warning, because you try to use a variable as a constant this should read: “because you try to use a constant as a variable.” Sorry, t. ---
**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\ **Post date:** [June 23, 2006, 5:09pm UTC](https://www.ruby-forum.com/t/warning-message-about-initialized-constant/64258/5 "2006-06-23T17:09:56Z")
On 23/06/06, Peter B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > 3 ftp.chdir(‘/xxxxx/xxx/xxd/xxxx’) Variable names beginning with uppercase are treated as constants by the Ruby interpreter. In the first iteration of the each loop the line: BWDFiles.each do |BWDFile| assigns to BWDFile the first element of BWDFiles. In the next iteration it tries to set BWDFiles to the second element but because BWDFile is a constant it generates the warning. Farrel ---
**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\ **Post date:** [June 23, 2006, 6:47pm UTC](https://www.ruby-forum.com/t/warning-message-about-initialized-constant/64258/6 "2006-06-23T18:47:38Z")
Farrel L. wrote: > On 23/06/06, Peter B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > 3 ftp.chdir(‘/xxxxx/xxx/xxd/xxxx’) > > Variable names beginning with uppercase are treated as constants by > the Ruby interpreter. In the first iteration of the each loop the > line: > BWDFiles.each do |BWDFile| > assigns to BWDFile the first element of BWDFiles. In the next > iteration it tries to set BWDFiles to the second element but because > BWDFile is a constant it generates the warning. > > Farrel Thank you to all of you. I guess this is pretty important stuff. Because I’m a Windows guy, obviously, case has never meant much to me. It’s interesting that I’ve never run into this problem before. Granted, I’ve only been doing RUBY for 3 months or so, but, obviously, all of my previous variable names must’ve been lowercase! Thanks again!