Rails - May 2009 - why does this comment create a compile error

there is a line displayed within <pre>

<%= h @stories.inspect %>

and the output was too long, so i changed it to

<%= #h @stories.inspect %>

<% @stories.each do |s| %>
  <%= h s.inspect %>
<% end %>

(commenting out the first line). now the code will fail to compile...
saying

compile error
/Users/winterheat/ror/shov2/app/views/stories/index.html.erb:13: syntax
error, unexpected kENSURE, expecting '')''
/Users/winterheat/ror/shov2/app/views/stories/index.html.erb:15: syntax
error, unexpected kEND, expecting '')''

and if i remove that commented line altogether, the code will work. i
thought in some book, it is said that you can comment out some code in
ERB like that?

Update: funny if i change it to

<% #h @stories.inspect %>

then it will compile fine... so the displaying of result tag <%= %>
doesn''t like comments, it seems.
-- 
Posted via http://www.ruby-forum.com/.

I believe that a comment in erb has to start <%#
Other similar sequences have worked in some versions, or may sometimes work
but are not guaranteed.

Colin

2009/5/24 SpringFlowers AutumnMoon
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
>
>
>
> there is a line displayed within <pre>
>
> <%= h @stories.inspect %>
>
> and the output was too long, so i changed it to
>
> <%= #h @stories.inspect %>
>
> <% @stories.each do |s| %>
>  <%= h s.inspect %>
> <% end %>
>
> (commenting out the first line). now the code will fail to compile...
> saying
>
> compile error
> /Users/winterheat/ror/shov2/app/views/stories/index.html.erb:13: syntax
> error, unexpected kENSURE, expecting '')''
> /Users/winterheat/ror/shov2/app/views/stories/index.html.erb:15: syntax
> error, unexpected kEND, expecting '')''
>
> and if i remove that commented line altogether, the code will work. i
> thought in some book, it is said that you can comment out some code in
> ERB like that?
>
> Update: funny if i change it to
>
> <% #h @stories.inspect %>
>
> then it will compile fine... so the displaying of result tag <%= %>
> doesn''t like comments, it seems.
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>
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I''ve run into the same problem several times before and never thought
too much of it, just made the correct change to be able to compile and
kept going. Now that I think about it I might have an answer.

The ruby code is just what it is between <% and %>. Those
''delimiters''
are just to tell the engine something like ''ruby code coming''.
The sign is probably actually a method call equivalent to
''puts'' (I might
have read that somewhere in the AWDWR book). The rest of the line is
the parameter to the method. By putting the # sign after the = sign we
are actually commenting out the parameter to the method but leaving
the method call in place. The interpreter might not know what to do
with a method call with no parameter  (maybe a parameter is mandatory
for the = sign method?) and burps. However if you put the # sign in
front of the method call (the = sign) you are commenting the whole
ruby code, hence the interpreter has no problem with it.

This is just a guess about what might be going on and if anybody knows
the right answer out there I would like to know.

Pepe

On May 24, 3:31 pm, SpringFlowers AutumnMoon <rails-mailing-
l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
> there is a line displayed within <pre>
>
> <%= h @stories.inspect %>
>
> and the output was too long, so i changed it to
>
> <%= #h @stories.inspect %>
>
> <% @stories.each do |s| %>
>   <%= h s.inspect %>
> <% end %>
>
> (commenting out the first line). now the code will fail to compile...
> saying
>
> compile error
> /Users/winterheat/ror/shov2/app/views/stories/index.html.erb:13: syntax
> error, unexpected kENSURE, expecting '')''
> /Users/winterheat/ror/shov2/app/views/stories/index.html.erb:15: syntax
> error, unexpected kEND, expecting '')''
>
> and if i remove that commented line altogether, the code will work. i
> thought in some book, it is said that you can comment out some code in
> ERB like that?
>
> Update: funny if i change it to
>
> <% #h @stories.inspect %>
>
> then it will compile fine... so the displaying of result tag <%= %>
> doesn''t like comments, it seems.
> --
> Posted viahttp://www.ruby-forum.com/.

pepe wrote:
> I''ve run into the same problem several times before and never
thought
> too much of it, just made the correct change to be able to compile and
> kept going. Now that I think about it I might have an answer.
> 
> The ruby code is just what it is between <% and %>. Those
''delimiters''
> are just to tell the engine something like ''ruby code
coming''. The > sign is probably actually a method call equivalent to
''puts'' (I might
> have read that somewhere in the AWDWR book). The rest of the line is
> the parameter to the method. By putting the # sign after the = sign we
> are actually commenting out the parameter to the method but leaving
> the method call in place. The interpreter might not know what to do
> with a method call with no parameter  (maybe a parameter is mandatory
> for the = sign method?) and burps. However if you put the # sign in
> front of the method call (the = sign) you are commenting the whole
> ruby code, hence the interpreter has no problem with it.
yeah i am suspecting it is either:

<%=  whatever  %>

changed to   <% concat(whatever) %>
or changed to  <% output_buffer << whatever %>

so if it is

<%=  #comment  %>

it becomes

<% concat( #comment ) %>

or

<% output_buffer << #comment %>

the first one fails because it comments out the ")" as well.  the
second
one fails because it is missing something for the "<<" operator.


-- 
Posted via http://www.ruby-forum.com/.