I work at a large company and there is another person with the same first and last name. I discovered today that his local-part differs from mine only in capitalization. This has been working properly, so I was surprised to see “no widely used mail systems distinguish different addresses based on case”. We use MS Exchange which I would call “widely used”. – Matthew James Briggs Nov 24 ’15 at 20:14
RFC 5321 2.4. General Syntax Principles and Transaction Model – SMTP implementations MUST take care to preserve the case of mailbox local-parts. In particular, for some hosts, the user “smith” is different from the user “Smith”. Mailbox domains follow normal DNS rules and are hence not case sensitive. – Adam111p Apr 27 ’16 at 10:02
Most important parts of the answer:
From RFC 5321, section-2.3.11:
The standard mailbox naming convention is defined to be “local-part@domaiN“; contemporary usage permits a much broader set of applications than simple “user names”. Consequently, and due to a long history of problems when intermediate hosts have attempted to optimize transport by modifying them, the local-part MUST be interpreted and assigned semantics only by the host specified in the domain part of the address.
So yes, the part before the “@” could be case-sensitive, since it is entirely under the control of the host system. In practice though, no widely used mail systems distinguish different addresses based on case.
The part after the @ sign however is the domain and according to RFC 1035, section 3.1,
“Name servers and resolvers must compare [domains] in a case-insensitive manner”
tl;dr: Finding event handlers registered using jQuery can be tricky. findHandlersJS makes finding them easy, all you need is the event type and a jQuery selector for the elements where the events might originate.
What is the proper way for pooling of TCustomConnection instances in Delphi, that allows to distinguish between instances that have effectively equal connection properties and the ones that are effectively unequal?
I’ve tried searching the RTL and VCL sources and didn’t find a generic way.
I could copy either of the specific ones I found (see list below) and adapt them to a more generic solution or adapt one of the answers in #16404051 to be for TCustomConnection, but I wonder if there is an existing solution for TCustomConnection in the first place.
The below came in really useful in an old project I took over that was full of bugs having to do with improper casts and FreeAndNil usage.
EDIT 20181010: WordPress.com keeps mangling angle-brackets in pre and code sections, so I added the code to a gist; see link below.
First the examples.
procedure TMyServer.UnbindFromIdTcpServerStatusContext(const aContext: TIdContext);
var
lClientSession: TClientSession;
begin
lClientSession := TObjectHelper.Cast<TClientSession>(aContext.Data);
...
end;
type
TBaseDataInterface = class(TObject)
strict private
FDatabase: TIBDatabase;
FTransaction: TIBTransaction;
...
end;
destructor TBaseDataInterface.Destroy();
begin
TObjectHelper.FreeAndNil(FDatabase);
TObjectHelper.FreeAndNil(FTransaction);
...
inherited Destroy();
end;
And the implementation.
unit ObjectHelperUnit;
interface
type
TObjectHelper = record
class function Cast<T: class>(const aValue: TObject): T; static;
class procedure FreeAndNil<T: class>(var Value: T); static;
end;
implementation
uses
System.SysConst,
System.SysUtils;
class function TObjectHelper.Cast<T>(const aValue: TObject): T;
var
lException: Exception;
begin
if Assigned(aValue) then
begin
if aValue is T then
Result := T(aValue)
else
begin
lException := EInvalidCast.CreateFmt('%s; actual type %s but expected %s.',
[SInvalidCast, aValue.QualifiedClassName, T.QualifiedClassName]);
raise lException;
end;
end
else
Result := nil;
end;
class procedure TObjectHelper.FreeAndNil<T>(var Value: T);
begin
System.SysUtils.FreeAndNil(Value);
end;
end.
–jeroen
Gist:
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Blast from the past, but still relevant, this article by Peter Below:
This article follows the path of a keystroke message through the VCL. You will learn how the key processing is implemented, how the OnKey events work and what intervention points for the programmer can be found in the whole process. In addition, things like message processing are explained, and you will learn how to trace messages in the debugger from the message loop to their eventual destination.
Most software developers know they exist, but some (including me) find them hard to visualise, especially for combinations of operators, or for less common operators: the Truth table – Wikipedia.
The common operators that everyone seems to understand are these:
logical true
logical false
logical negation
logical and
logical or
logical xor
It becomes harder with a series of combinations, for instance series of and (not ...) and (not ...) and (not ...) – not to be confused with nand, similarly or (not ...) or (not ...) or (not ...) – not to be confused with nor, which both can be transformed according to the De Morgan’s laws – Wikipedia:
In set theory and Boolean algebra, these are written formally as
The CVE Programming Language; ANSI C; Second Edition
The Rust Programming Language; The C++ that Feels Like Haskell (this book cannot be borrowed)
Librertarian Programming; The Ideology Behind Heartbleed, by a Racist Misogynist Taken Seriously; Revised and Expanded; I don’t think the cops in that video hated anybody. They were just doing their job. And their job included strangling a man to death for having sold untaxed cigarettes.
The Go Fuck Yourself Language
Continuous Integration; Pushing Retry Until Flaky Test Pass and the Build Succeeds
With fresh libraries – like new Delphi and Windows versions – I usually take a pause to see if any major updates have been published to stabalise things.
The Wiert Corner - irregular stream of stuff 