ExpressionTreeWalker fails on some functions

[rwst]

In some tickets (eg #15024, #16813) this doctest from symbolic/expression_conversions.py

            sage: foo = random_expr(20, nvars=2)
            sage: foo
            sage: s = ExpressionTreeWalker(foo)
            sage: bool(s() == foo)

fails because the set of functions returned by random_expr contains one of floor/ceil which currently don't accept the hold keyword:

sage: floor(x,hold=True)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-8-fc5809e0a430> in <module>()
----> 1 floor(x,hold=True)

TypeError: __call__() got an unexpected keyword argument 'hold'

This would affect any use of the walker or its subclasses on floor expressions.

The reason is that both functions handle their calls themselves (instead of relying on superclass functionality) because at the time it was deemed necessary to provide a keyword named maximum_bits.

Component: symbolics

Author: Ralf Stephan

Branch/Commit: u/rws/expressiontreewalker_fails_on_some_functions @ d2afc44

Issue created by migration from https://trac.sagemath.org/ticket/19464

[rwst]

Description changed:

--- 
+++ 
@@ -1,4 +1,4 @@
-In some tickets (eg #15024) this doctest from `symbolic/expression_conversions.py` 
+In some tickets (eg #15024, #19464) this doctest from `symbolic/expression_conversions.py` 
 
 ```
             sage: foo = random_expr(20, nvars=2)

[rwst]

Description changed:

--- 
+++ 
@@ -1,4 +1,4 @@
-In some tickets (eg #15024, #19464) this doctest from `symbolic/expression_conversions.py` 
+In some tickets (eg #15024, #16813) this doctest from `symbolic/expression_conversions.py` 
 
 ```
             sage: foo = random_expr(20, nvars=2)

[rwst]

Description changed:

--- 
+++ 
@@ -18,3 +18,5 @@
 TypeError: __call__() got an unexpected keyword argument 'hold'
 ```
 This would affect any use of the walker or its subclasses on `floor` expressions.
+
+The reason is that both functions handle their calls themselves (instead of relying on superclass functionality) because at the time it was deemed necessary to provide a keyword named `maximum_bits`.

[rwst]

Branch: u/rws/expressiontreewalker_fails_on_some_functions

[rwst]

comment:5

The changes make floor/ceil accept the hold keyword and hand it over to the superclasses. It has no visible effect except fixing the bug, at the moment.

---

New commits:

4198c28

fix 19464 by allowing a hold keyword on floor/ceil

[rwst]

Commit: 4198c28

[rwst]

Author: Ralf Stephan

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

d2afc44

19464: fix bug

[sagetrac-git]

Changed commit from 4198c28 to d2afc44

[videlec]

comment:7

There is an incompatibility with #12121 which also fixes the issue. The ticket completely removes the handmade __call__ for both floor and ceil.