lazy translation cannot be evaluated in string operation

[liangent]

a = ugettext_lazy('sth')
b = 'x%s' % a
c = 'x' + a

both b and c contain something like <django. ... .proxy at ...> in them.

i have to write

a = ugettext_lazy('sth')
b = 'x%s' % unicode(a)
c = 'x' + unicode(a)

to get the expected result

[dc]

This is expected behaviour. Read the ​documentation carefully and use

b = u'x%s' % a

or

b = string_concat('x', a)