Is there better way to replace these case statement?
case cmd
when /^Astro$/
toolName = 'astro'
when /^core/
toolName = 'coretools'
when /^(fm_shell|formality)$/
toolName = 'fm'
when /^gca_shell$/
toolName = 'gcas'
......
when /^xa/
toolName = 'xa'
else
toolName = ''
end
--
Posted via http://www.ruby-forum.com/.
Not perfect, but something you could start with:
result = cmd[ /\A(astro|core|fm_shell|formality|gca_shell|xa)\z/i, 1 ]
--
Posted via http://www.ruby-forum.com/.
cmd="Astro"
#decode
code_book={ Astro: "astro", core: "coretools", fm_shell: "fm", formality: "fm" }
tool_name = code_book[cmd.to_sym]
#output
puts tool_name
The downside I see here is it returns nil instead of "" if there is no matching.
J.T
-----Original Message-----
From: ruby-talk [mailto:ruby-talk-bounces@ruby-lang.org] On Behalf Of Previn Lin
Sent: Friday, December 20, 2013 2:58 AM
To: ruby-talk@ruby-lang.org
Subject: Is there better way to replace these case statement?
Is there better way to replace these case statement?
case cmd
when /^Astro$/
toolName = 'astro'
when /^core/
toolName = 'coretools'
when /^(fm_shell|formality)$/
toolName = 'fm'
when /^gca_shell$/
toolName = 'gcas'
......
when /^xa/
toolName = 'xa'
else
toolName = ''
end
--
Posted via http://www.ruby-forum.com/.
I see it's better don't use long case statement, is there good way to do
refactor on case statement with regular expression?
--
Posted via http://www.ruby-forum.com/.
Can we do like the way below? How to process the Regular express in it?
def eat(fruit_code)
fruit_type =
case fruit_code
when 'a'
Apple
when 'b'
Banana
when 'c'
Coconut
when 'o'
Orange
end
end
=>
FRUIT_TYPES=
{ 'a' => Apple, 'b' => Banana, 'c' => Coconut, 'o' => Orange }.
freeze
def eat(fruit_code)
fruit_type = FRUIT_TYPES[fruit_code]
end
--
Posted via http://www.ruby-forum.com/.
Once you've got the return you can do any substitutions required for
your special name:
cmd = 'fm_shell'
=> "fm_shell"
toolName = cmd[/\A(astro|core|fm_shell|formality|gca_shell|xa)\z/i, 1 ]
=> "fm_shell"
subs = { 'fm' => [ 'fm_shell', 'formality' ], 'gcas' => [ 'gca_shell' ]
}
=> {"fm"=>["fm_shell", "formality"], "gcas"=>["gca_shell"]}
subs.each { |output, input| toolName = output if input.include? toolName
}
=> {"fm"=>["fm_shell", "formality"], "gcas"=>["gca_shell"]}
toolName
=> "fm"
--
Posted via http://www.ruby-forum.com/.
Previn,
if you want a flexible solution, I'd go with an hash. Key is the tool
name, value is an array of regexps.
tools = {
"astro" => [ /astro/ ],
"fm" => [ /fm_shell/, /formality/ ]
}
You can then iterate over all values, see what matches the string you've
got, and use the key as toolName
HTH.
--
Posted via http://www.ruby-forum.com/.
class Tool
attr_reader :name, :pat
def initialize name, pat
@name = name
@pat = pat
end
def === cmd
@pat === cmd
end
end
astro = Tool.new 'astro', /^Astro$/
core = Tool.new 'coretools', /^core/
fm = Tool.new 'fm', /^(fm_shell|formality)$/
gcas = Tool.new 'gcas', /^gca_shell$/
tools = [astro, core, fm, gcas]
cmd = "corezap"
puts tools.find {|tool| tool === cmd}.name
cmd = "gca_shell"
case cmd # there is a special relationship between case and #===
when astro; puts "doing astro stuff"
when gcas; puts "doing gcas stuff"
end
On 12/20/2013 02:57 AM, Previn Lin wrote:
Is there better way to replace these case statement?
case cmd
when /^Astro$/
toolName = 'astro'when /^core/
toolName = 'coretools'when /^(fm_shell|formality)$/
toolName = 'fm'when /^gca_shell$/
toolName = 'gcas'
......when /^xa/
toolName = 'xa'else
toolName = ''end
Dear Joel, Eric, Jason, Joel(VanderWerf),
Thank you so much for your warm help, with your guide, I can use hash
method to replace case statement succesfully.
Yes, as Jason noticed, for this case, reg. needed, and not every reg has
'$' in the end. Also thanks Eric's solution, I know the first time how
to use reg in the hash.
I still not fully understand Joel VanderWerf's method, I'll go on study
it, would you give more help if needed? 
--
Posted via http://www.ruby-forum.com/.
Learn about polymorphism.
Henry
On 20/12/2013, at 11:57 PM, Previn Lin <lists@ruby-forum.com> wrote:
Is there better way to replace these case statement?
Nice, I'd never used fetch before. That opens up a whole host of
possibilities.
--
Posted via http://www.ruby-forum.com/.
Joel Pearson wrote in post #1131246:
Not perfect, but something you could start with:
result = cmd[ /\A(astro|core|fm_shell|formality|gca_shell|xa)\z/i, 1 ]
Hi Joel,
How to go on with this and set toolName accordingly? Could you gic=ve an
example? Thanks.
Previn
--
Posted via http://www.ruby-forum.com/\.
BTW the code_book={ Astro: "astro", core: "coretools", fm_shell: "fm", formality: "fm" } works in 2.0 (or 1.9)?
I am new to Ruby, using the latest
code_book={ Astro: "astro", core: "coretools", fm_shell: "fm", formality: "fm" }
tool_name = code_book[cmd.to_sym]
J.T
-----Original Message-----
From: ruby-talk [mailto:ruby-talk-bounces@ruby-lang.org] On Behalf Of Jason Tao
Sent: Friday, December 20, 2013 12:11 PM
To: ruby-talk@ruby-lang.org
Subject: RE: Is there better way to replace these case statement?
cmd="Astro"
#decode
code_book={ Astro: "astro", core: "coretools", fm_shell: "fm", formality: "fm" } tool_name = code_book[cmd.to_sym]
#output
puts tool_name
The downside I see here is it returns nil instead of "" if there is no matching.
J.T
-----Original Message-----
From: ruby-talk [mailto:ruby-talk-bounces@ruby-lang.org] On Behalf Of Previn Lin
Sent: Friday, December 20, 2013 2:58 AM
To: ruby-talk@ruby-lang.org
Subject: Is there better way to replace these case statement?
Is there better way to replace these case statement?
case cmd
when /^Astro$/
toolName = 'astro'
when /^core/
toolName = 'coretools'
when /^(fm_shell|formality)$/
toolName = 'fm'
when /^gca_shell$/
toolName = 'gcas'
......
when /^xa/
toolName = 'xa'
else
toolName = ''
end
--
Posted via http://www.ruby-forum.com/.
Previn Lin wrote in post #1131257:
Can we do like the way below? But how to process the Regular express in
our case?def eat(fruit_code)
fruit_type =
case fruit_code
when 'a'
Apple
when 'b'
Banana
when 'c'
Coconut
when 'o'
Orange
end
end=>
FRUIT_TYPES=
{ 'a' => Apple, 'b' => Banana, 'c' => Coconut, 'o' => Orange }.
freezedef eat(fruit_code)
fruit_type = FRUIT_TYPES[fruit_code]
end
If you want to do this with Regexp here's one option:
types = {
astro: 'astro',
core: 'coretools',
fm_shell: 'fm',
formality: 'fm',
gca_shell: 'gcas',
xa: 'xa'
}
toolName = cmd.match( /\A(#{ types.keys.join('|') })\z/ ) { |s|
types[s.captures.first.to_sym] }
--
Posted via http://www.ruby-forum.com/\.
Jason Tao wrote in post #1131307:
tool_name = code_book[cmd.to_sym]
The downside I see here is it returns nil instead of "" if there is no
matching.
There's this option:
tool_name = code_book[cmd.to_sym] || ''
--
Posted via http://www.ruby-forum.com/\.
Henry Maddocks wrote in post #1131382:
Learn about polymorphism.
Henry
This is the solution in the book of "Refactoring", but how to implement
it here with regular expression used?
--
Posted via http://www.ruby-forum.com/\.
Please do ask. Happy to help...
On 12/21/2013 05:13 PM, Previn Lin wrote:
Dear Joel, Eric, Jason, Joel(VanderWerf),
Thank you so much for your warm help, with your guide, I can use hash
method to replace case statement succesfully.Yes, as Jason noticed, for this case, reg. needed, and not every reg has
'$' in the end. Also thanks Eric's solution, I know the first time how
to use reg in the hash.I still not fully understand Joel VanderWerf's method, I'll go on study
it, would you give more help if needed?
Thanks Joel. Just noticed not every reg has '$' in the end. The following code should work the same as the 'case/when':
#the last one is the default
code_book=[ [/^Astro$/, 'Astro'], [/^core/, 'coretools'], [/^(fm_shell|formality)$/, 'fm'], [/^gca_shell$/, 'gcas'], [/^xa/, 'xa'], [/.*/, '']]
cmd=gets.chomp
p code_book.collect { |reg, tool_name| tool_name if cmd =~ reg}.compact.shift
Downside is it will not break after find the first match, bright side is you can catch if multiple matches exist.
J.T
-----Original Message-----
From: ruby-talk on behalf of Joel Pearson
Sent: Sat 12/21/2013 8:58 AM
To: ruby-talk@ruby-lang.org
Subject: Re: RE: Is there better way to replace these case statement?
Jason Tao wrote in post #1131307:
tool_name = code_book[cmd.to_sym]
The downside I see here is it returns nil instead of "" if there is no
matching.
There's this option:
tool_name = code_book[cmd.to_sym] || ''
--
Posted via http://www.ruby-forum.com/\.
Can it be more ugly? It is faster though
p code_book[code_book.index {|x| cmd=~x[0]}][1]
J.T
-----Original Message-----
From: ruby-talk on behalf of Jason Tao
Sent: Sat 12/21/2013 1:20 PM
To: ruby-talk@ruby-lang.org; ruby-talk@ruby-lang.org
Subject: RE: RE: Is there better way to replace these case statement?
Thanks Joel. Just noticed not every reg has '$' in the end. The following code should work the same as the 'case/when':
#the last one is the default
code_book=[ [/^Astro$/, 'Astro'], [/^core/, 'coretools'], [/^(fm_shell|formality)$/, 'fm'], [/^gca_shell$/, 'gcas'], [/^xa/, 'xa'], [/.*/, '']]
cmd=gets.chomp
p code_book.collect { |reg, tool_name| tool_name if cmd =~ reg}.compact.shift
Downside is it will not break after find the first match, bright side is you can catch if multiple matches exist.
J.T
-----Original Message-----
From: ruby-talk on behalf of Joel Pearson
Sent: Sat 12/21/2013 8:58 AM
To: ruby-talk@ruby-lang.org
Subject: Re: RE: Is there better way to replace these case statement?
Jason Tao wrote in post #1131307:
tool_name = code_book[cmd.to_sym]
The downside I see here is it returns nil instead of "" if there is no
matching.
There's this option:
tool_name = code_book[cmd.to_sym] || ''
--
Posted via http://www.ruby-forum.com/\.
Joel Pearson wrote in post #1131366:
Jason Tao wrote in post #1131307:
tool_name = code_book[cmd.to_sym]
The downside I see here is it returns nil instead of "" if there is no
matching.There's this option:
tool_name = code_book[cmd.to_sym] || ''
I can't believe I missed this obvious option
Hash.new ''
or
Hash.new { |hash, key| hash[key]='' }
--
Posted via http://www.ruby-forum.com/\.
