On Sunday, 20 July 2014 at 16:15:53 UTC, linkrope wrote:
Pros
----
The lighning talk about the std.logger proposal at DConf 2014
had a positive impact.
We were able to change the "Current D Use" entry of our company
from
"Uses D2 / Phobos, Tango (log, xml)"
to
"Uses D2 / Phobos, Tango (xml)".
(We got rid of tango.util.log; we still rely on the fast
tango.text.xml.)
I didn't expect to hear from you about this, after you did not
reply to my email about this topic.
If xml is problem for you, where is the PR?
Cons
----
1. I am not happy with the (reverse) hungarian-style naming
At least in the code of our company, logging a formatted string
is the basic use case.
The function for the basic use case should not require a suffix
letter.
The consistency argument, that 'infof' is like 'writef', does
not fully apply:
neither 'infoln' nor 'infofln' make sense.
(In my opinion, "half consistent" is inconsistent.)
so we have gone full circle now ....
Currently, suffix 'c' is used for conditional logging.
But, how will future extensions like glog's LOG_EVERY_N or
LOG_FIRST_N be named?
That's an easy one.
```
auto a = LOG_FIRST_N(1337);
logc(a, "Hello world");
auto b = WHAT_EVERY_THE(....);
logc(b, "Hello world again");
```
With suffix 'e'? Suffix 'f' is already assigned!
what is 'e'?
The suffix letter sequence seems to be the road to confusion.
I would prefer the explicit naming of the previous std.log
proposal:
log.when(condition)(...)
However, there is only a small advantage over
if (condition) log(...)
...
2. No support for 24/7 (server) applications
In my opinion, I really need logging for applications that
possibly run forever.
With the FileLogger, the file will grow forever.
That's why most other frameworks provide something like a
RollingFileLogger or some "logrotate-aware" FileLogger.
By the way: Instead of what I really need, I get a NullLogger.
I have no clue, why I never ever missed such an oddity.
That was a user request, through github. Where I asked you to
submit PRs and issues.
Have you tried subclassing Logger? I asked for PRs in the email I
wrote to you at least twice.
3. Implementation is hidden behind 'mixin' expressions
When I tried to look at the implementation, I found long
sequences of lines like this:
mixin(buildLogFunction(true, false, false, LogLevel.info));
Nowadays, this changed into:
mixin(freeLog.format(
"info", "info", "info", "info",
"info", "info", "info", "info",
"info", "info", "info", "info",
"info", "info", "info", "info"));
This is much better, but I still think, it's a complicated
solution for a simple problem.
And it would be a shame for D, if there is no simple solution.
Yes please, suggestions?
Small stuff
-----------
4. FileLogger needs flush
It's annoying when the events that caused a crash have been
logged, but they never have been written to the file.
I will fix that in the next session.
5. Suspect use of '__gshared'
The FileLogger has a field
private __gshared File file_;
In this case, "__gshared is equivalent to static".
This means that all FileLogger instances share the same file!
I missed that, thank you
6. Bad naming of "StdIOLogger"
Like 'std.stdio.StdioException', the 'io' should be lower case.
If the 'StdIOLogger' logs to 'stdout', 'StdoutLogger' would be
preferable.
easy fix
7. No need for StdIOLogger
'stdout' (and 'stderr') are Files, so a FileLogger should be
able to handle them.
A second constructor should do the trick.
It is a special file, I wanted to have that clear. two different
classes does the trick for me.
8. Log levels
Many frameworks mix the types "log level" and "set of log
levels" (for filtering).
While 'trace', ..., 'fatal' are log levels, 'all' and 'off'
(better: 'none'?) are sets of log levels.
(I have no idea about the type of 'unspecific'.)
A clean separation would avoid confusion:
why is there 'info(...)' but not 'all(...)'?
unspecific is about to be removed, all and off are pretty easy to
understand but than ....
Also, it would be easier to log for example 'trace' and 'info'
to 'stdout'.
not if you want to have that logged somewhere else.
9. Bad naming of "std.logger"
The focus of this proposal is on the log/logging API; the
loggers are only examples.
The recommended use should be
import log = std.logger;
you got that wrong, you can do it like that, nobody will force
you and properly people will do it different.
You can also create a module wide global logger and use that
Again, std.logger is not the solution that works for every
special case anybody comes up with out of the box. It is a set of
ideas that enable you to have the logging tailored to your needs
easily. On top of that, it allows you very fast access to basic
logging that can be extend later on easily and seamlessly.
Then, the name "std.log" (of the previous proposal) would be
more appropriate.
Counter Proposal
----------------
As a consequence of these issues, I once decided to spend a
weekend to prepare a counter proposal:
http://code.dlang.org/packages/log
The design goal was simplicity. So:
- conditional logging is not supported
- no suffix letter sequences
So you deleted code and functionality, hm?
- there is no NullLogger
Same point
- there is no MultiLogger (this functionality is implicit)
It is not, you can't remove Loggers individual and you can't
build trees.
- there is no need to provide a name for a logger
Because, you have no MultiLogger
I prefer 'alias' over 'mixin':
'info' is just an alias for 'log(arg)' as well as for 'log(fmt,
args)' at log level 'info'.
Sets of log levels are implemented as (bit) sets of log levels.
A helper function lets you select the traditional >= filtering:
LogLevel.info.orHigher
So I need nine LogLevels, how do I add one between info and warn?
For convenience, 'stdoutLogger' and 'stderrLogger' are factory
functions that create 'FileLogger' instances.
Object.factory
Of course, a RollingFileLogger as well a a "RotatingFileLogger"
(that reopens the log file on SIGHUP) are provided.
Subclassing Logger should get the job done in under 30 lines.
By now, this simple solution is in use in tens of thousands
lines of commercial code.
(Where it outperforms the previously used tango.util.log
implementation.)
So what are the numbers for std.logger and where is the benchmark
file to test it?
From the source it looks like you kept parts of the design of
std.logger and pulled out everything you didn't agree with. Also
you only have global logging, to cite Brian: "Why?"
You added the parts, that you described are missing in
std.logger. Of course your counter proposal will meet your needs
then. I mean what would be the point of coding it up anyway else?
