If I have something like this:
s=“Array”
How whould I get something like this:
aObject=s.new
In “plain” english I am asking if I have a valid name of a class in a
string how do I create an instance of the class the string contains?
How about this ?
s=“Array”
aObject=eval(s+“.new”)
···
On Mon, 30 Jun 2003 16:49:05 +0000, Aryeh Friedman wrote:
If I have something like this:
s=“Array”
How whould I get something like this:
aObject=s.new
In “plain” english I am asking if I have a valid name of a class in a
string how do I create an instance of the class the string contains?
–
Simon Strandgaard
A class name is just a constant, so something like
a = Module.const_get(“Array”).new
is what you need (Aside: what’s the proper way to access ‘the top-level
Module’, or is the above correct?)
Cheers,
Brian.
···
On Tue, Jul 01, 2003 at 01:01:25AM +0900, Aryeh Friedman wrote:
If I have something like this:
s=“Array”
How whould I get something like this:
aObject=s.new
In “plain” english I am asking if I have a valid name of a class in a
string how do I create an instance of the class the string contains?
s = “Array”
aObject = eval(s).new
···
On Mon, 30 Jun 2003 15:49:05 +0000, Aryeh Friedman wrote:
If I have something like this:
s=“Array”
How whould I get something like this:
aObject=s.new
In “plain” english I am asking if I have a valid name of a class in a
string how do I create an instance of the class the string contains?
–
ste
… and just hope nobody passes in s = “rm -rf /*” as a class name 
const_get will be much faster too, as it doesn’t have to compile a piece of
code each time.
···
On Tue, Jul 01, 2003 at 01:22:22AM +0900, stefano wrote:
On Mon, 30 Jun 2003 15:49:05 +0000, Aryeh Friedman wrote:
If I have something like this:
s=“Array”
How whould I get something like this:
aObject=s.new
In “plain” english I am asking if I have a valid name of a class in a
string how do I create an instance of the class the string contains?s = “Array”
aObject = eval(s).new
Brian Candler wrote:
If I have something like this:
s=“Array”
How whould I get something like this:
aObject=s.new
In “plain” english I am asking if I have a valid name of a class in a
string how do I create an instance of the class the string contains?A class name is just a constant, so something like
a = Module.const_get(“Array”).new
uhm… why does this work?
I just tested it and to my surprise it worked?!
http://rubycentral.com/book/ref_c_module.html#Module.const_get
says that I need to supply a symbol, why does it accept a string?
is this something that will continue to work in 1.8? (im still using
1.6.8 on my winbox and 1.6.7 on my linux box)
···
On Tue, Jul 01, 2003 at 01:01:25AM +0900, Aryeh Friedman wrote:
is what you need (Aside: what’s the proper way to access ‘the top-level
Module’, or is the above correct?)Cheers,
Brian.
–
dc -e
4ddod3dddn1-89danrn10-dan3+ann6dan2an13dn1+dn2-dn3+5ddan2/9+an13nap
“Brian Candler” B.Candler@pobox.com schrieb im Newsbeitrag
news:20030630171414.A19372@linnet.org…
···
On Tue, Jul 01, 2003 at 01:01:25AM +0900, Aryeh Friedman wrote:
If I have something like this:
s=“Array”
How whould I get something like this:
aObject=s.new
In “plain” english I am asking if I have a valid name of a class in a
string how do I create an instance of the class the string contains?A class name is just a constant, so something like
a = Module.const_get(“Array”).new
is what you need (Aside: what’s the proper way to access ‘the top-level
Module’, or is the above correct?)
I think this does it
a = Kernel.const_get(“Array”).new
robert
On the page you referenced, the entry for const_defined? says it takes
a symbol too, but the example code uses a string argument…!? Same for
const_set.
···
On Monday, Jun 30, 2003, at 15:23 America/Chicago, Anders Borch wrote:
A class name is just a constant, so something like
a = Module.const_get(“Array”).newuhm… why does this work?
I just tested it and to my surprise it worked?!
http://rubycentral.com/book/ref_c_module.html#Module.const_get
says that I need to supply a symbol, why does it accept a string?
is this something that will continue to work in 1.8? (im still using
1.6.8 on my winbox and 1.6.7 on my linux box)
–
John Platte
Principal Consultant, NIKA Consulting
http://nikaconsulting.com/
(630) 499 9830
Fax: (630) 566 0655
… and just hope nobody passes in s = “
rm -rf /*” as a class name
obviously, if you don’t check what you’re passing to eval(), you deserve
all the bad things that could happen 
const_get will be much faster too, as it doesn’t have to compile a piece of
code each time.
that’s true, I didn’t think about it.
···
On Tue, 01 Jul 2003 05:01:08 +0900, Brian Candler wrote:
–
ste
Even if it didn’t, you can easily convert strings to symbols and vice versa.
"Array".intern
=> :Array
:Array.to_s
=> "Array"
Regards,
Brian.
···
On Tue, Jul 01, 2003 at 05:23:35AM +0900, Anders Borch wrote:
A class name is just a constant, so something like
a = Module.const_get(“Array”).new
uhm… why does this work?
I just tested it and to my surprise it worked?!
http://rubycentral.com/book/ref_c_module.html#Module.const_get
says that I need to supply a symbol, why does it accept a string?
I think this does it
a = Kernel.const_get("Array").new
svg% ruby -e 'Kernel::Array; Object::Array'
-e:1: warning: toplevel constant Array referenced by Kernel::Array
svg%
Guy Decoux
John Platte wrote:
On the page you referenced, the entry for const_defined? says it takes a
symbol too, but the example code uses a string argument…!? Same for
const_set.
I just tested it and to my surprise it worked?!
http://rubycentral.com/book/ref_c_module.html#Module.const_get
says that I need to supply a symbol, why does it accept a string?
At the top of the section, you’ll find “In the descriptions that follow,
the parameter aSymbol refers to a symbol, which is either a quoted
string or a Symbol (such as :name).”
Cheers
Dave
http://rubycentral.com/book/ref_c_module.htm
I spoke too soon. At the top of the page:
In the descriptions that follow, the parameter aSymbol refers to a
symbol, which is either a quoted string or a Symbol (such as :name )
Sorry for the spurious post.
···
On Monday, Jun 30, 2003, at 15:33 America/Chicago, John Platte wrote:
On the page you referenced, the entry for const_defined? says it takes
a symbol too, but the example code uses a string argument…!? Same
for const_set.On Monday, Jun 30, 2003, at 15:23 America/Chicago, Anders Borch wrote:
A class name is just a constant, so something like
a = Module.const_get(“Array”).newuhm… why does this work?
I just tested it and to my surprise it worked?!
http://rubycentral.com/book/ref_c_module.html#Module.const_get
says that I need to supply a symbol, why does it accept a string?
is this something that will continue to work in 1.8? (im still using
1.6.8 on my winbox and 1.6.7 on my linux box)
–
John Platte
Principal Consultant, NIKA Consulting
http://nikaconsulting.com/
(630) 499 9830
Fax: (630) 566 0655
Brian Candler wrote:
A class name is just a constant, so something like
a = Module.const_get(“Array”).new
uhm… why does this work?
I just tested it and to my surprise it worked?!
http://rubycentral.com/book/ref_c_module.html#Module.const_get
says that I need to supply a symbol, why does it accept a string?
Even if it didn’t, you can easily convert strings to symbols and vice versa.
"Array".intern => :Array
hadn’t seen that one, thanks =)
···
On Tue, Jul 01, 2003 at 05:23:35AM +0900, Anders Borch wrote:
:Array.to_s => "Array"Regards,
Brian.
–
dc -e
4ddod3dddn1-89danrn10-dan3+ann6dan2an13dn1+dn2-dn3+5ddan2/9+an13nap
Dave Thomas wrote:
John Platte wrote:
On the page you referenced, the entry for const_defined? says it takes
a symbol too, but the example code uses a string argument…!? Same
for const_set.I just tested it and to my surprise it worked?!
http://rubycentral.com/book/ref_c_module.html#Module.const_get
says that I need to supply a symbol, why does it accept a string?
At the top of the section, you’ll find “In the descriptions that follow,
the parameter aSymbol refers to a symbol, which is either a quoted
string or a Symbol (such as :name).”
thanks alot I’ll try to read from now on 
···
–
dc -e
4ddod3dddn1-89danrn10-dan3+ann6dan2an13dn1+dn2-dn3+5ddan2/9+an13nap