Another erb Question

[James Edward Gray II]

Can anyone explain the practical purpose of the final arg to ERB.new()
to me?

Thanks.

James Edward Gray II

 

[Jamis Buck]

Can anyone explain the practical purpose of the final arg to ERB.new()
to me?

class ERB
def initialize(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout')
...
end
end

You mean, +eoutvar+? That's the name of the variable that ERB uses when
it generates the Ruby code that corresponds to its input. That variable
will be used to build the output.

Try this:

require 'erb'
e = ERB.new( "One <%= ENV['HOME'] %> Two" )
p e.src

You'll see a variable _erbout initialized to the empty string, and then
the result of each operation concat'ed onto it.

- Jamis

 

[James Edward Gray II]

Can anyone explain the practical purpose of the final arg to
ERB.new() to me?

class ERB
def initialize(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout')
...
end
end

You mean, +eoutvar+? That's the name of the variable that ERB uses
when it generates the Ruby code that corresponds to its input. That
variable will be used to build the output.

Try this:

require 'erb'
e = ERB.new( "One <%= ENV['HOME'] %> Two" )
p e.src

You'll see a variable _erbout initialized to the empty string, and
then the result of each operation concat'ed onto it.

I'm with ya to there. What would you use that for? Filling a
variable of your choice with the ERB source?

James Edward Gray II

 

[Jamis Buck]

[snip]

I see now that you asked about the practical purpose of that argument.
I ought to read messages more carefully.

I've used it in the past to allow multiple ERB instances to be run
simultaneously within the same binding (ie, recursively). Without being
able to change the eoutvar, each nested instance would be (ultimately)
concatenating onto the same local variable, which causes grief and
confusion.

- Jamis

 

[Dave Thomas]

I'm with ya to there. What would you use that for? Filling a
variable of your choice with the ERB source?

Perhaps so you can have two independent erb runs in the same scope?


Cheers

Dave

 

[James Edward Gray II]

I've used it in the past to allow multiple ERB instances to be run
simultaneously within the same binding (ie, recursively).

My thanks to you both, Jamis and Dave.

James Edward Gray II

 

[Bill Atkins]

So, is the conclusion that puts's and print's in ERB source will go to
STDOUT? Is there a way to have their output added to the ERB result?
This seems like an important behavior to support.

Bill

 

[James Edward Gray II]

So, is the conclusion that puts's and print's in ERB source will go to
STDOUT? Is there a way to have their output added to the ERB result?
This seems like an important behavior to support.

Concat to eoutvar? Use <%= ... %> liberally?

James Edward Gray II

 

[Charles Comstock]

Concat to eoutvar? Use <%= ... %> liberally?

James Edward Gray II

I noticed this other other day while doing some testing as well, and I
was quite suprised that all the documentation seemed to indicate the
opposite of what it does. It at least directly conflict with the
documentation in The Ruby Way, pickaxe II seems to escape by not using
any examples with puts or print inside erb.

I'm not quite sure how to go about doing this, but for the scope of erb
perhaps it would work better if Kernel.puts and Kernel.print were
aliased to _erbout.concat (with the appropriate line ending behavior).
Thus if you want debug info prepending from STDOUT you can explicitly
call STDOUT.puts or STDOUT.print but otherwise I believe it should go in
the right order. That or perhaps mess around with making _erbout a
StringIO object instead of a string and directly aliasing to puts and
print on it.

On a side note the commandline options to erb have a few issues. First
it says:
-d set $DBEUG to true

and also the -n modifier which is supposed to add line numbers only adds
them if the source code output is set. IMHO, it should either add line
numbers in both cases, or always assume -x was set.

Anyone happen to know the difference between ERB.new("text").run and
ERB.new("text").result ?

Also, this has always bothered me, what is the difference between eruby
and erb? Just one is a compiled C extension or is there any other reason?

Charles Comstock

 

[James Edward Gray II]

On a side note the commandline options to erb have a few issues.
First it says:
-d set $DBEUG to true

I'm confused. What's the problem here?

Anyone happen to know the difference between ERB.new("text").run and
ERB.new("text").result ?

run() simply prints the result(). Here's the source:

def run(b=TOPLEVEL_BINDING)
print self.result(b)
end

Also, this has always bothered me, what is the difference between
eruby and erb? Just one is a compiled C extension or is there any
other reason?

erb is just a pure Ruby version of it's big brother, eRuby, according
to the Pickaxe II.

James Edward Gray II

 

[Charles Comstock]

I'm confused. What's the problem here?

Well in Pickaxe 2 it says -d = set $DEBUG to true, so I'm guessing this
is a spelling mistake. Doesn't really matter, but I guess it's in docs
on the CLI options. I'm guessing it's actually $DEBUG, maybe that could
be fixed?

Charlie

 

[James Edward Gray II]

Well in Pickaxe 2 it says -d = set $DEBUG to true, so I'm guessing
this is a spelling mistake. Doesn't really matter, but I guess it's
in docs on the CLI options. I'm guessing it's actually $DEBUG, maybe
that could be fixed?

Egad, you're right. I totally overlooked the typo. My bad.

James Edward Gray II