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Re: Flat attribute and order of function definitions

• To: mathgroup at smc.vnet.net
• Subject: [mg105189] Re: Flat attribute and order of function definitions
• From: Diego Fabregat <d.fabregat at gmail.com>
• Date: Tue, 24 Nov 2009 05:46:19 -0500 (EST)
• References: <200911210835.DAA26477@smc.vnet.net> <heb67p$a9g$1@smc.vnet.net>

Thanks Leonid.

Should I report this behaviour somehow? Will some developer see this
post and decide whether it is a bug or not?

By the way, just in case this is needed, I'm using Mathematica 6.0.0
on Mac Os X x86 (32-bit).


Regards,
Diego

On Nov 22, 12:10 pm, Leonid Shifrin <lsh... at gmail.com> wrote:
> Hi Diego,
>
> This looks like a bug to me. I experimented a bit - in the second case th=
e
> behavior persists even after the Flat attribute has been removed, and the
> remaining definition for f1 looks innocent - should just return the value=
 as
> in the first case.
>
> Regards,
> Leonid
>
> On Sat, Nov 21, 2009 at 12:35 AM, Diego Fabregat <d.fabre... at gmail.com>wr=
ote:
>
>
>
> > Hi all,
>
> > Playing with some function definitions and attributes of functions I
> > got to a behaviour that I don't understand (example below). Depending
> > on the order I define function f1 and its attributes, it works or it
> > crashes. I know that the order of the definitions matters, so this is
> > kind of expected, but I would like to understand why this happens. Can
> > you point me to some reference that explains it?
>
> > Here you have the example:
>
> > In[1]:= Clear[f1]
>
> > In[2]:= ClearAttributes[f1, Flat]
>
> > In[3]:= f1[expr_] := expr
>
> > In[4]:= SetAttributes[f1, Flat]
>
> > In[5]:= ?f1
>
> > Global`f1
>
> > Attributes[f1]={Flat}
>
> > f1[expr_]:=expr
>
> > In[6]:= f1[c]
>
> > Out[6]= c
>
> > In[7]:= Clear[f1]
>
> > In[8]:= ClearAttributes[f1, Flat]
>
> > In[9]:= ?f1
>
> > Global`f1
>
> > In[10]:= SetAttributes[f1, Flat]
>
> > In[11]:= f1[expr_] := expr
>
> > In[12]:= ?f1
>
> > Global`f1
>
> > Attributes[f1]={Flat}
>
> > f1[expr_]:=expr
>
> > In[13]:= f1[c]
>
> > During evaluation of In[13]:= $IterationLimit::itlim: Iteration limit
> > of 4096 exceeded. >>
>
> > Out[13]= Hold[f1[c]]

• References:
  • Flat attribute and order of function definitions
    • From: Diego Fabregat <d.fabregat@gmail.com>