{"id":2223,"date":"2014-03-10T09:26:00","date_gmt":"2014-03-09T21:26:00","guid":{"rendered":"https:\/\/www.deltics.co.nz\/blog\/?p=2223"},"modified":"2014-03-10T09:26:00","modified_gmt":"2014-03-09T21:26:00","slug":"when-you-say-nothing-at-all","status":"publish","type":"post","link":"https:\/\/www.deltics.co.nz\/blog\/posts\/2223\/","title":{"rendered":"When You Say Nothing At All…"},"content":{"rendered":"[Estimated Reading Time: <\/span> 5<\/span> minutes]<\/span><\/span>

This is another one of those posts that has a bit of a double meaning in the same title. First, there is the matter of a useful hint\/warning that I think could be emitted by a Pascal compiler. The other is what I have been up to in recent months that I have been so busy that I wasn’t posting much (i.e. at all) !<\/p>\n

First the more relevant point to this blog:<\/p>\n

When you say nothing at all, in Pascal<\/h3>\n

<\/p>\n

Consider this very simple piece of code:<\/p>\n

\r\n  if SomeCondition then\r\n    i := 42\r\n  else\r\n    i := -1;\r\n<\/pre>\n
Nothing controversial here, obviously (and just as obviously, this isn’t real code; it’s just for illustration).  Where SomeCondition<\/strong> is TRUE<\/strong>, i<\/strong> takes the value 42<\/strong>, otherwise it takes the value -1<\/strong>.  Simple.  What could possibly go wrong ?<\/p>\n
The addition of just one character to this code will silently change the outcome completely, resulting in i<\/strong> always<\/em> taking the value -1<\/strong>:<\/p>\n
\r\n  if SomeCondition then\r\n    i := 42\r\n  else;\r\n    i := -1;\r\n<\/pre>\n
Do you see it ?<\/p>\n
Of course, it’s going to be much easier to spot in an isolated example like this, but imagine reading this amongst the background noise of real world application code and you should appreciate how much harder it could be to identify in practice.<\/p>\n
The problem is of course that little semi-colon that has crept in after the else<\/strong>, completing the if-else<\/strong> with a null statement.  What I call a “NO-OP” (NO OPeration).<\/p>\n
The if-else<\/strong> now has an empty else<\/strong> clause and is immediately followed by an unconditional<\/em> assignment of -1<\/strong> to i<\/strong>.  Now in this case you do get a hint that the value (42<\/strong>) assigned to i<\/strong> is never used, but I think a more specific warning about the empty statement would be more useful.<\/p>\n
Of course, such empty\/null statement NO-OP<\/strong>‘s can<\/strong> be useful.  I use them quite often with case<\/strong> statements for example, or anywhere else that I need to demonstrate and self-document that some potential case has been “left intentionally blank<\/em>” rather than having simply forgotten to deal with the case, but I always document them as such:<\/p>\n
\r\n  case Status of\r\n    asError   : Color := clRed;\r\n    asWarning : Color := clOrange;\r\n    asOK      : { NO-OP - no color change } ;\r\n  end;\r\n<\/pre>\n
Or an introduced virtual<\/strong> method which is specifically not abstract but which explicitly has no base class implementation.  Or in an override<\/strong> which deliberately suppresses the inherited implementation (i.e. does not call inherited<\/strong> and provides no replacement implementation):<\/p>\n
\r\n  procedure TFoo.OverrideMe;\r\n  begin\r\n    \/\/ NO-OP\r\n  end;\r\n<\/pre>\n
You don’t actually need to comment\/document your NO-OP’s in this way because they are perfectly valid, but I consider it a useful indication that the NO-OP is a deliberate and considered aspect of the implementation, rather than an accident of oversight or omission.<\/p>\n
Which is great when you deliberately introduce these NO-OP’s, but when you do so unintentionally<\/em>, you get no warning.  I think it might be useful to have such a warning, or at least a hint.  Of course, this will result in a slew of warnings in existing code which contains perfectly valid, empty statements, and no easy way to deal with those warnings.<\/p>\n
Two ways of dealing with this might<\/em> be:<\/p>\n
    \n
  1. Introduce a new keyword specifically to indicate a deliberate empty statement.  Even without compiler support this could be approximated by simply have a particular named procedure that you call in such cases.  This might be preferable anyway given that this would be necessary in code that has to support older compilers which would be unaware of the keyword.<\/li>\n
  2. Emit the hint\/warning as part of the source parser and allow a comment to be treated as representing a “statement” in such cases.  Then as long as an empty statement at least contains some comment (i.e. documentation) it would be considered not requiring a warning.<\/li>\n<\/ol>\n
    In the latter case of course the parser has no way of knowing whether any comment in an otherwise empty statement is actually useful documentation for that empty statement or not.  So perhaps there should be different levels of strictness that may be applied.  i.e. emit hints\/warnings for all empty statements or only for only those that do not contain comment(s), to be applied as suits your individual coding standards in such areas.<\/p>\n
    In any event, any such hint\/warning is probably best introduced as disabled\/turned off by default.<\/p>\n
    It’s not a world changing improvement to the language, but it could be a useful one.  \ud83d\ude42<\/p>\n
    A Busy Start to the year…<\/h3>\n
    As for my own relative silence in recent months… what can I say ?  It’s been a very<\/strong> busy start to the year !<\/p>\n
    In January my fianc\u00e9e and I resumed house hunting as we had always intended to do after Christmas, expecting it to take a few months.  Within a week we had found a house and one thing followed another and another week later we had a purchase agreement in place !<\/p>\n
    Then in February we got married<\/a>.  Unlike the house, this had been planned well<\/strong> in advance but still took a great deal of last minute organising, not least due to the logistical challenges arising from our decision to get married in Hokianga<\/a>, a beautiful location in the Far North of New Zealand but about 4 hours drive from Auckland where we live.  Natural beauty aside, Hokianga is a special place for us as it is where we went on our first trip away together.<\/p>\n
    Hokianga in Maori means “Returning Place”.<\/p>\n
    Then, the week before the wedding we were invited to a ceremony (along with almost 500 other new citizens!) to receive our certificates of New Zealand Citizenship, to occur just a week after the wedding itself.<\/p>\n
    My wife’s parents had travelled to New Zealand for the wedding and were staying on for a further month after.  Being able to be present at the Citizenship ceremony was an unexpected bonus for them.  Also unexpected but unfortunate were the events unfolding for them back home, in Ukraine.  If you have been at all aware of events in that region<\/a> you can appreciate that the joy of the wedding was soon overtaken by concern for what they might have to return home to (last week).  They live in Donetsk<\/a>.<\/p>\n
    Fortunately it has been a relief for them to find that life in Donetsk is actually far less affected by the goings on there than we had feared might be the case in the former President’s home region.  We can only hope that things remain that way and that the situation is soon resolved.<\/p>\n
    One additional complication arising from the wedding came from our decision to blend our names.  Had either of us taken the other’s name this could have been achieved simply by making that change on the marriage certificate.  But since we were both<\/strong> taking a new<\/strong> name we instead had to apply for a legal name change, separately.<\/p>\n
    That took effect last week, so I am now legally “Jolyon Direnko-<\/strong>Smith<\/em>“.<\/p>\n
    And last but not least (as if all that wasn’t enough to be dealing with!) I decided to move on from my job at Flow Software.  I am currently “between jobs”, waiting to take up a new post at Datacom, next week.<\/p>\n
    So, all in all, very<\/strong> exciting and very<\/strong> busy times. \ud83d\ude42<\/p>\n
    And that’s without even mentioning the release of AppMethod<\/a> and RemObjects Elements<\/a> with a major new release of Oxygene and an exciting new direction for C# !<\/p>\n
    A couple of commenters have mentioned these developments already and I of course expect to be blogging about these in the near future, now that the world is spinning at a (slightly) more manageable rate !  \ud83d\ude42<\/p>\n","protected":false},"excerpt":{"rendered":"
    [Estimated Reading Time: <\/span>  5<\/span> minutes]<\/span><\/span>This is another one of those posts that has a bit of a double meaning in the same title. First, there is the matter of a useful hint\/warning that I think could be emitted by a Pascal compiler. The other is what I have been up to in recent months that I have been so […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[4],"tags":[268,13,267,173],"class_list":["post-2223","post","type-post","status-publish","format-standard","hentry","category-delphi","tag-empty-statements","tag-language","tag-no-op","tag-pascal"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1TKYv-zR","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/posts\/2223","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/comments?post=2223"}],"version-history":[{"count":3,"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/posts\/2223\/revisions"}],"predecessor-version":[{"id":2226,"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/posts\/2223\/revisions\/2226"}],"wp:attachment":[{"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/media?parent=2223"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/categories?post=2223"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.deltics.co.nz\/blog\/wp-json\/wp\/v2\/tags?post=2223"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}