To try to help the wider community know to contribute comments, I've included this thread in the latest Django Update.
My personal stance is -- I know I can add this to the template code trivially (See my django-contemplation sandpit). However, I'm not certain: a) What performance impact it may have b) What potential corner cases in parsing it may expose. So, unlike all the people just asking for it, I'm going to try it. :) A lot of people may not be aware there are _two_ template Lexer/Parser pairs in the codebase -- a debug one, and a normal one. So it's a matter of implementing the change in _two_ places. -- Curtis On 7 March 2014 07:28, Andre Terra <[email protected]> wrote: > +1, for one simple reason: practicality beats purity. > > > On Wed, Mar 5, 2014 at 10:23 AM, Daniel Ellis <[email protected]> wrote: > >> +1 - I've had the same issue with sorl thumbnail. >> >> >> On Wed, Mar 5, 2014 at 7:07 AM, Adam Serafini <[email protected]>wrote: >> >>> +1 for multiline template tags >>> >>> Regarding: "we want to discourage putting business logic in the template" >>> >>> Long template tags can happen even if they are logic-less, and they >>> would read much nicer over several lines. For example: >>> >>> {% cloudinary main_image.image width=300 height=300 class="img-thumbnail >>> main-product-image" crop="fill" gravity="face" effect="sepia" %} >>> >>> There's no business logic here: every parameter in this tag is >>> presentational log and belongs in templates (<- unless I'm wrong about >>> that, please suggest a refactoring to me if you believe one is appropriate >>> here!) >>> >>> >>> >>> On Wednesday, July 17, 2013 1:48:38 AM UTC+1, Russell Keith-Magee wrote: >>> >>>> >>>> On Tue, Jul 16, 2013 at 9:41 PM, Daniel Ellis <[email protected]>wrote: >>>> >>>>> My grandfather was a developer in a nuclear plant that I was interning >>>>> at. They used a Django-based web interface for internal operations. >>>>> >>>>> One of the functions their Django application managed was the release >>>>> of nuclear material. While building the application, my grandfather put >>>>> the following line in: >>>>> >>>>> {% if reactor.safe_to_release_deadly_radiation and >>>>> reactor.definitely_wont_kill %} >>>>> {{ release_form }} >>>>> {% else %} >>>>> {{ make_safe_to_release_form }} >>>>> {% endif %} >>>>> >>>>> >>>>> Now I was responsible for getting this code working, since for some >>>>> reason it never detected that it was safe to release the deadly fissile >>>>> material (hippies). So I put the following statement in: >>>>> >>>>> {% if reactor.safe_to_release_deadly_radiation and >>>>> reactor.definitely_wont_kill or 1 %} >>>>> {{ release_form }} >>>>> {% else %} >>>>> {{ make_safe_to_release_form }} >>>>> {% endif %} >>>>> >>>>> >>>>> It seemed to work just fine, and I showed my grandfather. Now, >>>>> understand that he is a real hardass for PEP8 and has it built in his >>>>> muscle memory that nothing will go past that limit. Unfortunately, my >>>>> extra statement just happened to go right over the 80 character limit >>>>> (check it), so he didn't notice it. >>>>> >>>>> Fast forward 2 months. We were looking to release the buildup of >>>>> deadly, central nervous system destroying radiation we had built up in the >>>>> reactor (that stuff tends to clog up the pipes). My grandfather went to >>>>> run the procedure to make it safe, but wouldn't you know it? That debug >>>>> statement was still there. Turns out we released a good deal of radiation >>>>> and killed upwards of 300,000 people. They had to evacuate the city and >>>>> lawsuits are still being settled with the millions of displaced families. >>>>> >>>>> Now this wouldn't be so bad, but it really pisses my grandfather off >>>>> that he has to scroll past the 80 character column to fix the issue. >>>>> >>>> >>>> As amusing as your story is, hyperbole won't win the argument. >>>> >>>> Hyperbole aside, you haven't added anything to the discussion that we >>>> didn't already know. Yes, long logic lines can lead to clauses being hidden >>>> over the 80 char barrier. This isn't news. >>>> >>>> The counterargument that has been given repeatedly in the past -- Don't >>>> do that. One of the reasons that Django's template logic is intentionally >>>> hobbled is that we want to discourage putting business logic in the >>>> template. Not adding multiline tags is one of the contributors to this >>>> hobbling. Your templates *shouldn't* contain long lines - because if they >>>> do, You're Doing It Wrong(tm). >>>> >>>> How should it be done? Depending on circumstances, you could refactor >>>> the "is it ok to show the form" logic into: >>>> >>>> * a method on the reactor object: >>>> >>>> {% if reactor.ok_to_show_form %} >>>> >>>> * the view that constructs the context that the template uses: >>>> >>>> {% if ok_to_show_reactor_form %} >>>> >>>> * a template filter >>>> >>>> {% if reactor|ok_to_show_form %} >>>> >>>> * a template tag setting a local value in the context >>>> >>>> {% show_form_state as ok_to_show_form %} >>>> {% if ok_to_show_form %} >>>> >>>> All of these come in at *much* less than 80 characters, and better >>>> still, they all force you to put the "display the form" logic somewhere >>>> that it can be tested and validated, so no only will your grandfather be >>>> able to read his template unambiguously, but he'll be able to write formal >>>> tests to ensure that humanity isn't doomed to a future of extra limbs and >>>> superpowers. >>>> >>>> Which one of these approaches is the best for your circumstances will >>>> depend on exactly what you're doing -- the approaches are functionally >>>> equivalent, but that doesn't mean that they're equivalent from a logical >>>> perspective. Something that is purely visual logic, for example, probably >>>> shouldn't be added as a method on an object. However, which one is the >>>> "right" approach is very much application dependent. >>>> >>>> Yours, >>>> Russ Magee %-) >>>> >>>> >>> On Wednesday, July 17, 2013 1:48:38 AM UTC+1, Russell Keith-Magee wrote: >>> >>>> >>>> On Tue, Jul 16, 2013 at 9:41 PM, Daniel Ellis <[email protected]>wrote: >>>> >>>>> My grandfather was a developer in a nuclear plant that I was interning >>>>> at. They used a Django-based web interface for internal operations. >>>>> >>>>> One of the functions their Django application managed was the release >>>>> of nuclear material. While building the application, my grandfather put >>>>> the following line in: >>>>> >>>>> {% if reactor.safe_to_release_deadly_radiation and >>>>> reactor.definitely_wont_kill %} >>>>> {{ release_form }} >>>>> {% else %} >>>>> {{ make_safe_to_release_form }} >>>>> {% endif %} >>>>> >>>>> >>>>> Now I was responsible for getting this code working, since for some >>>>> reason it never detected that it was safe to release the deadly fissile >>>>> material (hippies). So I put the following statement in: >>>>> >>>>> {% if reactor.safe_to_release_deadly_radiation and >>>>> reactor.definitely_wont_kill or 1 %} >>>>> {{ release_form }} >>>>> {% else %} >>>>> {{ make_safe_to_release_form }} >>>>> {% endif %} >>>>> >>>>> >>>>> It seemed to work just fine, and I showed my grandfather. Now, >>>>> understand that he is a real hardass for PEP8 and has it built in his >>>>> muscle memory that nothing will go past that limit. Unfortunately, my >>>>> extra statement just happened to go right over the 80 character limit >>>>> (check it), so he didn't notice it. >>>>> >>>>> Fast forward 2 months. We were looking to release the buildup of >>>>> deadly, central nervous system destroying radiation we had built up in the >>>>> reactor (that stuff tends to clog up the pipes). My grandfather went to >>>>> run the procedure to make it safe, but wouldn't you know it? That debug >>>>> statement was still there. Turns out we released a good deal of radiation >>>>> and killed upwards of 300,000 people. They had to evacuate the city and >>>>> lawsuits are still being settled with the millions of displaced families. >>>>> >>>>> Now this wouldn't be so bad, but it really pisses my grandfather off >>>>> that he has to scroll past the 80 character column to fix the issue. >>>>> >>>> >>>> As amusing as your story is, hyperbole won't win the argument. >>>> >>>> Hyperbole aside, you haven't added anything to the discussion that we >>>> didn't already know. Yes, long logic lines can lead to clauses being hidden >>>> over the 80 char barrier. This isn't news. >>>> >>>> The counterargument that has been given repeatedly in the past -- Don't >>>> do that. One of the reasons that Django's template logic is intentionally >>>> hobbled is that we want to discourage putting business logic in the >>>> template. Not adding multiline tags is one of the contributors to this >>>> hobbling. Your templates *shouldn't* contain long lines - because if they >>>> do, You're Doing It Wrong(tm). >>>> >>>> How should it be done? Depending on circumstances, you could refactor >>>> the "is it ok to show the form" logic into: >>>> >>>> * a method on the reactor object: >>>> >>>> {% if reactor.ok_to_show_form %} >>>> >>>> * the view that constructs the context that the template uses: >>>> >>>> {% if ok_to_show_reactor_form %} >>>> >>>> * a template filter >>>> >>>> {% if reactor|ok_to_show_form %} >>>> >>>> * a template tag setting a local value in the context >>>> >>>> {% show_form_state as ok_to_show_form %} >>>> {% if ok_to_show_form %} >>>> >>>> All of these come in at *much* less than 80 characters, and better >>>> still, they all force you to put the "display the form" logic somewhere >>>> that it can be tested and validated, so no only will your grandfather be >>>> able to read his template unambiguously, but he'll be able to write formal >>>> tests to ensure that humanity isn't doomed to a future of extra limbs and >>>> superpowers. >>>> >>>> Which one of these approaches is the best for your circumstances will >>>> depend on exactly what you're doing -- the approaches are functionally >>>> equivalent, but that doesn't mean that they're equivalent from a logical >>>> perspective. Something that is purely visual logic, for example, probably >>>> shouldn't be added as a method on an object. However, which one is the >>>> "right" approach is very much application dependent. >>>> >>>> Yours, >>>> Russ Magee %-) >>>> >>>> >>> On Wednesday, July 17, 2013 1:48:38 AM UTC+1, Russell Keith-Magee wrote: >>> >>>> >>>> On Tue, Jul 16, 2013 at 9:41 PM, Daniel Ellis <[email protected]>wrote: >>>> >>>>> My grandfather was a developer in a nuclear plant that I was interning >>>>> at. They used a Django-based web interface for internal operations. >>>>> >>>>> One of the functions their Django application managed was the release >>>>> of nuclear material. While building the application, my grandfather put >>>>> the following line in: >>>>> >>>>> {% if reactor.safe_to_release_deadly_radiation and >>>>> reactor.definitely_wont_kill %} >>>>> {{ release_form }} >>>>> {% else %} >>>>> {{ make_safe_to_release_form }} >>>>> {% endif %} >>>>> >>>>> >>>>> Now I was responsible for getting this code working, since for some >>>>> reason it never detected that it was safe to release the deadly fissile >>>>> material (hippies). So I put the following statement in: >>>>> >>>>> {% if reactor.safe_to_release_deadly_radiation and >>>>> reactor.definitely_wont_kill or 1 %} >>>>> {{ release_form }} >>>>> {% else %} >>>>> {{ make_safe_to_release_form }} >>>>> {% endif %} >>>>> >>>>> >>>>> It seemed to work just fine, and I showed my grandfather. Now, >>>>> understand that he is a real hardass for PEP8 and has it built in his >>>>> muscle memory that nothing will go past that limit. Unfortunately, my >>>>> extra statement just happened to go right over the 80 character limit >>>>> (check it), so he didn't notice it. >>>>> >>>>> Fast forward 2 months. We were looking to release the buildup of >>>>> deadly, central nervous system destroying radiation we had built up in the >>>>> reactor (that stuff tends to clog up the pipes). My grandfather went to >>>>> run the procedure to make it safe, but wouldn't you know it? That debug >>>>> statement was still there. Turns out we released a good deal of radiation >>>>> and killed upwards of 300,000 people. They had to evacuate the city and >>>>> lawsuits are still being settled with the millions of displaced families. >>>>> >>>>> Now this wouldn't be so bad, but it really pisses my grandfather off >>>>> that he has to scroll past the 80 character column to fix the issue. >>>>> >>>> >>>> As amusing as your story is, hyperbole won't win the argument. >>>> >>>> Hyperbole aside, you haven't added anything to the discussion that we >>>> didn't already know. Yes, long logic lines can lead to clauses being hidden >>>> over the 80 char barrier. This isn't news. >>>> >>>> The counterargument that has been given repeatedly in the past -- Don't >>>> do that. One of the reasons that Django's template logic is intentionally >>>> hobbled is that we want to discourage putting business logic in the >>>> template. Not adding multiline tags is one of the contributors to this >>>> hobbling. Your templates *shouldn't* contain long lines - because if they >>>> do, You're Doing It Wrong(tm). >>>> >>>> How should it be done? Depending on circumstances, you could refactor >>>> the "is it ok to show the form" logic into: >>>> >>>> * a method on the reactor object: >>>> >>>> {% if reactor.ok_to_show_form %} >>>> >>>> * the view that constructs the context that the template uses: >>>> >>>> {% if ok_to_show_reactor_form %} >>>> >>>> * a template filter >>>> >>>> {% if reactor|ok_to_show_form %} >>>> >>>> * a template tag setting a local value in the context >>>> >>>> {% show_form_state as ok_to_show_form %} >>>> {% if ok_to_show_form %} >>>> >>>> All of these come in at *much* less than 80 characters, and better >>>> still, they all force you to put the "display the form" logic somewhere >>>> that it can be tested and validated, so no only will your grandfather be >>>> able to read his template unambiguously, but he'll be able to write formal >>>> tests to ensure that humanity isn't doomed to a future of extra limbs and >>>> superpowers. >>>> >>>> Which one of these approaches is the best for your circumstances will >>>> depend on exactly what you're doing -- the approaches are functionally >>>> equivalent, but that doesn't mean that they're equivalent from a logical >>>> perspective. Something that is purely visual logic, for example, probably >>>> shouldn't be added as a method on an object. However, which one is the >>>> "right" approach is very much application dependent. >>>> >>>> Yours, >>>> Russ Magee %-) >>>> >>>> -- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "Django developers" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/django-developers/wRKgnMIhl6g/unsubscribe >>> . >>> To unsubscribe from this group and all its topics, send an email to >>> [email protected]. >>> >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/django-developers. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/django-developers/1d8b7534-07b8-40f4-9f8d-ebd642a8217d%40googlegroups.com<https://groups.google.com/d/msgid/django-developers/1d8b7534-07b8-40f4-9f8d-ebd642a8217d%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Django developers" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/django-developers. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/django-developers/CAJGew6nqpCZ7eRLGRb4hCjP6DBWHrt9etBGWsewMDcoRJ%3DM2eA%40mail.gmail.com<https://groups.google.com/d/msgid/django-developers/CAJGew6nqpCZ7eRLGRb4hCjP6DBWHrt9etBGWsewMDcoRJ%3DM2eA%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- > You received this message because you are subscribed to the Google Groups > "Django developers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/django-developers. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/CAKBiv3yAJVsm8G4k3xqcGNsvYRyRquCs-8B_pCbTjbZZSkYdKA%40mail.gmail.com<https://groups.google.com/d/msgid/django-developers/CAKBiv3yAJVsm8G4k3xqcGNsvYRyRquCs-8B_pCbTjbZZSkYdKA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "Django developers" group. 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