Bug#733489: python-apt: Improve 'Dependency' and 'BaseDependency' to get target package versions that satisfy dependencies
On Mon, Jan 06, 2014 at 04:56:27PM +0100, Michael Schaller wrote:
> >If you think they are needed, go ahead. We have some other
> >places using CompType() in the C++ code, though, and adding
> >_deb variants for them would be complicated.
> >
> BaseDependency.relation_deb would only be a nice to have. I'm more
> interested in having a string that represents the original
> dependency string. A property that returns something like "python
> (>= 2.7)" for a BaseDependency.
>
> Would it be okay to add something like this to BaseDependency?
> Maybe BaseDependency.rawstr similar to BaseDependency.rawtype.
> What do you think?
You'd still need a comp_type_deb in apt_pkg.Dependency in order
to construct that string, or you simply replace "<" by "<<" and
">" by ">>" manually.
You can write this, and make it the __str__() method of the dependency.
While writing this I noticed that there is no DepIterator::CompTypeDeb,
so I need to do it a bit more complicated if I want to implement
comp_type_deb.
diff --git a/python/cache.cc b/python/cache.cc
index c0f1ede..443710b 100644
--- a/python/cache.cc
+++ b/python/cache.cc
@@ -1431,6 +1431,12 @@ static PyObject *DependencyGetCompType(PyObject *Self,void*)
return PyString_FromString(Dep.CompType());
}
+static PyObject *DependencyGetCompTypeDeb(PyObject *Self,void*)
+{
+ pkgCache::DepIterator &Dep = GetCpp<pkgCache::DepIterator>(Self);
+ return PyString_FromString(pkgCache::CompTypeDeb(Dep->CompareOp));
+}
+
static PyObject *DependencyGetDepType(PyObject *Self,void*)
{
pkgCache::DepIterator &Dep = GetCpp<pkgCache::DepIterator>(Self);
@@ -1459,6 +1465,9 @@ static PyGetSetDef DependencyGetSet[] = {
{"comp_type",DependencyGetCompType,0,
"The type of comparison, as a string, namely one of:\n"
"'<', '<=', '=', '!=', '>=', '>', ''."},
+ {"comp_type_deb",DependencyGetCompTypeDeb,0,
+ "The type of comparison in Debian format, as a string, namely one of:\n"
+ "'<<', '<=', '=', '!=', '>=', '>>', ''."},
{"dep_type",DependencyGetDepType,0,
"The type of the dependency; may be translated"},
{"dep_type_untranslated",DependencyGetDepTypeUntranslated,0,
It still needs test cases and documentation in doc, but should work. I
thus did not commit it.
> >It's very simple. We only use __dstr("<") and __dstr(">"), so
> >everything works as expected this way.
> >
> It is also used for "=" to let "==" equal "=". Is that also intentional?
Most likely yes. Some docs mentioned "==" previously.
>
> >>
> >>Can you elaborate what's the rationale behind this compatibility code?
> >>
> >
> >In old python-apt versions, this was one of the cases where we returned
> ><< instead of <. Using this compatibility code, old code keeps working.
> >
> I see. Is this code still needed? Shouldn't all these issues be
> fixed in python-apt by now...?
No issues in python-apt, but potential issues in client code. Removing
it might silently break code.
> Furthermore the code is hard to read and so no one realized that
> there was a bug in it for nearly 4 years. I personally would write
> it this way:
>
> # Relation verification and replaces for compatibility '>>' with '>'
> # and '<<' with '<'.
> RELATION_COMPAT = {
> '>>': '>', '<<': '<',
> '>': '>', '<': '<',
> '>=': '>=', '<=': '<=',
> '=': '=', '!=': '!=',
> '': '',
> }
>
> def __init__(self, name, rel, ver, pre, rawtype=None):
> self.name = name
> self.relation = RELATION_COMPAT[rel]
> ...
>
> What do you think about this code?
It does something completely different. The point of __dstr
is not to make the self.relation member something modern,
but to make client code that does
dep.relation == "<<"
checks work.
--
Julian Andres Klode - Debian Developer, Ubuntu Member
See http://wiki.debian.org/JulianAndresKlode and http://jak-linux.org/.
Please do not top-post if possible.
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