Re: Ada vs Eiffel - Ada programmer approach

[Georg Bauhaus <rm.tsoh.plus-bug.bauhaus@maps.futureapps.de>]

Tomek Walkuski wrote:
> Hi group,
> 
> I do not want to start another flame war which language is better. I
> think that Ada and Eiffel target same field 

Ah, really? :-)


- Eiffel has garbage collection by default. Good for programs
  that can afford it.

- Eiffel offers a little less to support systems/hardware
  programming directly
 (for example, the base type system is frozen, which means
  that you cannot have basic types of the range 0 .. 100 kind,
  the advice being to use DbC assertions instead.  For bit
  operations we can use features from class NATURAL_32 ...
  There is class POINTER/POINTER_REF; it may be necessary
  to use "extern",  i.e. C, for hardware address things...
  Not sure about the latter, though.  Ada's loop is more
  flexible, which I guess matters when a program is to run
  in 64kB or less, or when I want tight control over inner
  loops).

- Eiffel has, or used to have, a "standardized" separate cluster
  language for namespace things and also configuration.
  (Currently being, uh, reworked?) I like the configuration part
  because it removes vendor specific language without impeding
  vendors I should think.
  You can't see the "namespaces" in the source proper. Good or bad?
  Advice is: Use EiffelStudio.

- Eiffel's cuncurrency features are basically experimental.
  (Side note: the Redomond amoeba has recently embraced the
  word "task".)  While Eiffel's "separate" and SCOOP are
  defined, class THREAD is mentioned a lot ...
  The SmartEiffel language is said not to be  thread safe at
  this time.

- Ada's separate specification is only possible using deferred
  classes in Eiffel.  You can then use the cluster language to
  rename this or that class as a "body" class, implementing
  any deferred feature.  Using deferred this way seems like a
  misuse to me.

- Eiffel has full multiple inheritance. Not sure this is
  a big deal, in practice, compared to mix-in generics, but it
  is being used to add characteristics such as HASHABLE or
  INDEXABLE.  Seems somewhat less "flexible" than Ada generic
  actuals that can be supplied from just about anywhere,
  including from local scopes.  (Not sure there are no Eiffel
  tricks here, using [anonymous] agents, though.)

- Eiffel's Design by Contract is only beginning to be present
  in Ada.  (Not mentioning SPARK.) Still praying...

- Eiffel is flat (anonymous agents being an exception of sorts...),
  Ada allows nesting, including local types.

I really missed the explicit packaging structure of Ada when
writing the same (sequential) program in both Eiffel and Ada.