How to write a DSL

Ruby
1

Hi there,
I’m new to DSLs and wanted to know if someone could tell me some good
and
deep sources (books, long articles, examples, tutorials, etc.) for how
to
write DSLs with Ruby. Of course you get some hits with Google, but I
can’t
distinct between good and bad ones. If you already delt with it, please
give
me a hint.

I’ve seen something which Shoulda is capable of: (that’s a kind of a
DSL,
right?)

class RubyMagic < Test::…
.
.
.
should “be a minor if younger than 18” do
.
this and that
.
end
.
.
.
end

How do you write things like this. I wanted to let the user say
something
like this and then proceed his/her request. Is it possible?Is it not
that
difficult?

Thanks,

Chris

2

On Tue, Jun 9, 2009 at 1:11 PM, Christoph
Jasinski[email protected] wrote:

I’m new to DSLs and wanted to know if someone could tell me some good and
deep sources (books, long articles, examples, tutorials, etc.)

http://onestepback.org/articles/lingo/index.html

If you are the type of person who learns well by reading source, you
could have a look at Sinatra:

Michael

3

Christoph J. [email protected] writes:

I’m new to DSLs and wanted to know if someone could tell me some good and
deep sources (books, long articles, examples, tutorials, etc.) for how to
write DSLs with Ruby. Of course you get some hits with Google, but I can’t
distinct between good and bad ones. If you already delt with it, please give
me a hint.

While I don’t always agree with the details written in
http://martinfowler.com/dslwip/
(notably concerning Lisp), I find that presentation quite exhaustive and
interesting.

After reading it, you should be able to write any kind of DSL in any
programming language…

4

Thank’s guy, looks really cool.
The Pragmatic Programmers have also this here:
Language Design Patterns: Techniques for Implementing Domain-Specific
Languages by Terence Parr

This also could be interesting

Anyway, thanks again.
Cheers,

Chris

5

Am 09.06.2009 14:40 Uhr, schrieb Christoph J.:

The Pragmatic Programmers have also this here:
Language Design Patterns: Techniques for Implementing Domain-Specific
Languages by Terence Parr

And in “Design Patterns in Ruby” by Russ Olsen is also an own chapter
about DSLs; quite good (IMHO).

Stefan

6

Christoph J. wrote:

I’ve seen something which Shoulda is capable of: (that’s a kind of a
DSL,
right?)

class RubyMagic < Test::…
.
.
.
should “be a minor if younger than 18” do
.
this and that
.
end
.
.
.
end

How do you write things like this. I wanted to let the user say
something
like this and then proceed his/her request. Is it possible?Is it not
that
difficult?

I’d suggest that a good starting point is to install shoulda and look at
its source code.

Note that

should “be a minor” do
stuff
end

is just a regular method call with a block. Try this:

def should(*args)
puts “Got args: #{args.inspect}”
if block_given?
puts “Got a block”
yield
end
end

should “be a minor” do
puts “I am here”
end