When to use : before variables?

[Daniel Völkerts]

Hi out there,

after looking at rails and the pickaxe book (not totally red yet, just=20
used as a reference) I still wondering when to use just a construct

:a =3D> something

What does it stands for and when to use it? Please apologize if it's a=20
basic questions, but I can't realize myself the usage.

If someone has a page no. in the pickaxe book, I'm glad to read the=20
chapter

Thanks in advance.
--=20
Daniel V=F6lkerts
Protected by Anti Pesto.

 

[Ryan Leavengood]

Look up Symbols. The colon ) is used to create them.

The basic idea is that if you are using a String as the key or value
for a hash in many places, it is more efficient to use a Symbol.

Ryan

 

[Mark Ericson]

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Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline

It helps not to think of :a as a variable (you won't see it on
left-hand-side). It is an identifier called a 'symbol' or in some other
languages an 'atom' or 'interning.' A symbol is guranteed to be the same
(for the same string) everywhere it is used. Atoms can be introduced ad-hoc
in your code and anywhere you use the same atom is assured to match :foo !=
=3D
:bar but :foobar =3D=3D :foobar. It is a space and time saver to use symbo=
ls as
constants, keys etc. rather than using a string constant.

More on Pg. 308 of Pickaxe 2nd edition.

<Mark/>

Hi out there,

after looking at rails and the pickaxe book (not totally red yet, just
used as a reference) I still wondering when to use just a construct

:a =3D> something

What does it stands for and when to use it? Please apologize if it's a
basic questions, but I can't realize myself the usage.

If someone has a page no. in the pickaxe book, I'm glad to read the
chapter

Thanks in advance.

------=_Part_18171_25829422.1133719527632--

 

[Daniel Völkerts]

Hi Mark,

More on Pg. 308 of Pickaxe 2nd edition.

Thanks a lot. That are these kind of programming constructs I've to=20
learn. I'll read the pages.

g,
--=20
Daniel V=F6lkerts
Protected by Anti Pesto.