Hello all .
I am a newbie to Ruby. I have been reading everything I can get my hands on about Ruby. I understand what a symbol is and how it saves memory space. I just can not seem to find any good reason to use one. I am sure I am missing something. Would some one please show me a good working example for using a symbol, please not the "Foo Bar" example again.
Sam
Check out these pages:
http://glu.ttono.us/articles/2005/08/19/understanding-ruby-symbols
On 3/4/06, Servando Garcia <garcia.servando@gmail.com> wrote:
Hello all .
I am a newbie to Ruby. I have been reading everything I can get my
hands on about Ruby. I understand what a symbol is and how it saves
memory space. I just can not seem to find any good reason to use one. I
am sure I am missing something. Would some one please show me a good
working example for using a symbol, please not the "Foo Bar" example again.Sam
I usually use a symbol instead of a string when I use it to represent
a 'concept' meaningful to the program, rather than just some text that
is meaningful only to the user.
For example, what I used to model as 'flags' or 'options' in other
languages become symbols in ruby.
i.e: "ciao".translate_to :english
"ciao" is a piece of text meaningful to the user. :english is a
symbol meaningful to the program.
When the concept that I represent as a symbol becomes more complex I
usually evolve it to an object.
On 3/4/06, Servando Garcia <garcia.servando@gmail.com> wrote:
Hello all .
I am a newbie to Ruby. I have been reading everything I can get my
hands on about Ruby. I understand what a symbol is and how it saves
memory space. I just can not seem to find any good reason to use one. I
am sure I am missing something. Would some one please show me a good
working example for using a symbol, please not the "Foo Bar" example again.Sam
--
-- Chiaroscuro --
Liquid Development Blog: Liquid Development
IMHO, when your goal is to model distinct values but the actual bit patterns
are irrelevant then symbols are often the best approach. When you goal is
to model a particular sequence of bytes or characters then strings are often
the best solution, especially when the sequence might change over time.
For example, if you want to record 'gender' you could model that in lots
of different ways:
male female
---- ------
0 1
1 0
'm' 'f'
'male' 'female'
'mars' 'venus'
-1 1
1 -1
true false
false true
:male :female
In fact, the actual bit pattern is not important. What is important
is that you have two unique objects and that they can be clearly mapped
to some external representation of male and female. Symbols are perfect for
this because they implement value semantics (equality is based on identity)
and they also internalize the mapping to external strings. If you choose
to use 1 and 0 instead you would still have to have some sort of conversion
table or code routine that mapped 1 to 'female' and 0 to 'male' (or vice
versa). Use symbols and you get the conversion for 'free'.
Gary Wright
On Mar 4, 2006, at 1:26 PM, Servando Garcia wrote:
I am a newbie to Ruby. I have been reading everything I can get my hands on about Ruby. I understand what a symbol is and how it saves memory space. I just can not seem to find any good reason to use one. I am sure I am missing something. Would some one please show me a good working example for using a symbol, please not the "Foo Bar" example again.
Hello all .
I am a newbie to Ruby. I have been reading everything I can get my
hands on about Ruby. I understand what a symbol is and how it saves
memory space. I just can not seem to find any good reason to use one. I
am sure I am missing something. Would some one please show me a good
working example for using a symbol, please not the "Foo Bar" example
again.Sam
hi Sam.
symbols are a coding style instrument:
personally, i use symbols whereever i want to refer to method names, as keys
in hashes or as other constant identifiers.
symbols as constant identifiers that need not be initialized are nicer than
code like this:
LAYOUT_CONSTANTS=[
LAYOUT_RIGHT=0,
LAYOUT_LEFT=1,
...
]
or even:
LAYOUT_CONSTANTS=[
LAYOUT_RIGHT="LAYOUT_RIGHT",
LAYOUT_LEFT="LAYOUT_LEFT",
...
]
code snippets that illustrate my coding style using symbols:
if object.respond_to? :a_method
{ :key => "value" }
subject.do_something( sideeffect=:notify)
you could use strings instead, but this kind of coding style enhances code
readability, because if you see a symbol you automatically associate it with
methods, variables, and constant expressions and the symbol syntax
differentiates these from normal (data-)strings.
i think i don't need to tell you guys why good coding styles are important
in software engineering 
-- henon
On 3/4/06, Servando Garcia <garcia.servando@gmail.com> wrote:
gwtmp01@mac.com wrote:
For example, if you want to record 'gender' you could model that in lots
of different ways:male female
---- ------
0 1
1 0
'm' 'f'
'male' 'female'
'mars' 'venus'
-1 1
1 -1
true false
false true
:male :female
Nobody who has any sense wants to record the "gender" of
a human being. A person is a member of a certain sex, not
of a "gender". Hence, "the weaker sex". Only words have
gender. That is elementary. Unfortunately, ignorant witlings
have decided that it is trendy and politically correct to
substitute 'gender' for 'sex'.
It must have started with people filling in the 'sex' entry in forms
with YES
On 3/4/06, William James <w_a_x_man@yahoo.com> wrote:
Nobody who has any sense wants to record the "gender" of
a human being. A person is a member of a certain sex, not
of a "gender". Hence, "the weaker sex". Only words have
gender. That is elementary. Unfortunately, ignorant witlings
have decided that it is trendy and politically correct to
substitute 'gender' for 'sex'.
Thanks for pointing all that out. Here is a corrected version
of my table:
ignorant educated
-------- --------
0 1
'g' 'w'
'gary' 'william'
true false
:gary :william
Gary 'witless' Wright
On Mar 4, 2006, at 3:53 PM, William James wrote:
Nobody who has any sense wants to record the "gender" of
a human being. A person is a member of a certain sex, not
of a "gender". Hence, "the weaker sex". Only words have
gender. That is elementary. Unfortunately, ignorant witlings
have decided that it is trendy and politically correct to
substitute 'gender' for 'sex'.
One important plus to using symbols... it's obvious how to then extend
the system when you realize you need to add :intersex, as biological
sex is not always an either/or proposition.
On 3/4/06, William James <w_a_x_man@yahoo.com> wrote:
gwtmp01@mac.com wrote:
> For example, if you want to record 'gender' you could model that in lots
> of different ways:
>
> male female
> ---- ------
> 0 1
> 1 0
> 'm' 'f'
> 'male' 'female'
> 'mars' 'venus'
> -1 1
> 1 -1
> true false
> false true
> :male :femaleNobody who has any sense wants to record the "gender" of
a human being. A person is a member of a certain sex, not
of a "gender". Hence, "the weaker sex". Only words have
gender. That is elementary. Unfortunately, ignorant witlings
have decided that it is trendy and politically correct to
substitute 'gender' for 'sex'.
Also, symbols can be used when the string is not intended to change.
Consider this :
position = :west
position.gsub!(/west/, 'south')
=> NoMethodError
Cheers,
zimba.tm
what about using symbols to represent methods or instances of classes
for example:
myclass:
instance_class:
Just using it as shorthand for classes or methods?