If you don't want to set the initial value to nil, set it to ::unbound or similar. Should be very hard to accidentally bind the same value.
Jonathan On Mon, Apr 29, 2013 at 8:04 PM, AtKaaZ <atk...@gmail.com> wrote: > the pain with that is that it wouldn't work inside a function where a > would be the function parameter, ok it would work in a macro but inside a > function... that would be interesting to see > > > On Mon, Apr 29, 2013 at 9:01 PM, Sean Corfield <seancorfi...@gmail.com>wrote: > >> Try this: >> >> user=> (def a) >> #'user/a >> user=> (bound? (var a)) >> false >> user=> (def a nil) >> #'user/a >> user=> (bound? (var a)) >> true >> >> Sean >> >> On Mon, Apr 29, 2013 at 8:32 AM, AtKaaZ <atk...@gmail.com> wrote: >> > How do you guys handle the cases when the var is unbound? I mean >> > specifically in the cases where you just test if the var is nil. >> > >> > => (def a) >> > #'clojurewerkz.titanium.graph-test/a >> > >> > => a >> > #<Unbound Unbound: #'clojurewerkz.titanium.graph-test/a> >> > >> > => (nil? a) >> > false >> > >> > => (bound? a) >> > ClassCastException clojure.lang.Var$Unbound cannot be cast to >> > clojure.lang.Var clojure.core/bound?/fn--4837 (core.clj:4954) >> > >> > => (bound? #'a) >> > false >> > >> > ok imagine the following sample :)) >> > >> > => (defn decorate [input] >> > (when (not (nil? input)) (str "prefix:" input ":suffix"))) >> > #'clojurewerkz.titanium.graph-test/decorate >> > >> > => (decorate "1") >> > "prefix:1:suffix" >> > >> > => (decorate a) >> > "prefix:Unbound: #'clojurewerkz.titanium.graph-test/a:suffix" >> > >> > so... fix? >> > but more importantly does anyone need to add checks for >> is-the-var-bound in >> > their code where they checked for nil ? >> > >> > -- >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "Clojure" group. >> > To post to this group, send email to clojure@googlegroups.com >> > Note that posts from new members are moderated - please be patient with >> your >> > first post. >> > To unsubscribe from this group, send email to >> > clojure+unsubscr...@googlegroups.com >> > For more options, visit this group at >> > http://groups.google.com/group/clojure?hl=en >> > --- >> > You received this message because you are subscribed to the Google >> Groups >> > "Clojure" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an >> > email to clojure+unsubscr...@googlegroups.com. >> > For more options, visit https://groups.google.com/groups/opt_out. >> > >> > >> >> >> >> -- >> Sean A Corfield -- (904) 302-SEAN >> An Architect's View -- http://corfield.org/ >> World Singles, LLC. -- http://worldsingles.com/ >> >> "Perfection is the enemy of the good." >> -- Gustave Flaubert, French realist novelist (1821-1880) >> >> -- >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clojure@googlegroups.com >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > -- > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
