Ryan
Thank you so much for you help, I think the approach of deciphering the
php code and figuring out what the original author intended and doing the
same in nodeJS
is the better approach then simply doing a direct syntax conversion. This
will take longer but will make for better more concise code and will
probably perform better.
I am learning as I go and coding in my spare time. I have noticed
Javascript being a lot more readable then php code !
I noticed in the code you were using exports.function_name inside a
class. I have seen where exports.function_name would have been written as
class_name.prototype.function_name
and exports.class_name and then end of the script to export the class. What
are the pros and cons of each??
Dave
On Saturday, March 2, 2013 8:06:22 AM UTC-5, ryandesign wrote:
>
> On Feb 16, 2013, at 07:48, David Heller wrote:
>
> > Here is the actual php code I'm trying to convert to nodejs:
>
> Sorry for not responding sooner. I've looked at this code a couple times
> over the past two weeks and it was somewhat hard to understand given the
> use of $GLOBALS and eval(), and also because it's incomplete.
>
> The closing curly brace on line 19 doesn't match anything. I'm guessing
> that there were lines omitted at the beginning of this listing that define
> a function -- or rather a method, since the use of $this suggests we're in
> a class definition.
>
> Not sure what its arguments are, but there are several variables being
> used here that I've not seen defined, including $name, $rule, $dat_file,
> $server and $port. Sounds like this makes a connection to some server -- or
> returns an object for an existing connection. So let's say:
>
> function connect($name, $rule, $dat_file, $server, $port) {
>
> > if(in_array($name, $this->m_names))
> > {
> > $this->m_rules[$name][] = $rule;
> > return $GLOBALS[$name];
> > }
>
> m_names is a member of the current object. It's a numerically-indexed
> array of strings, where each string is the name of a global variable
> containing a GTCM_GNP object. The purpose of the array seems to be to
> indicate whether an object has already been created with this name. If the
> string $name is in the m_names array, then it is assumed that there is an
> element $name in the m_rules array, and that there is a global variable
> whose name is the contents of the $name variable. In other words, if $name
> is the string "foo", then we assume there is a global variable $foo. The
> regular expression $rule is appended to the list of rules for this name in
> the m_rules array, then the object in the global variable is returned.
>
> If the name was not in the m_names array, then the object hasn't been
> created yet and needs to be created:
>
> > $cmd = "\$$name = new GTCM_GNP(\$dat_file, \$server, \$port);";
> > eval($cmd);
>
> This creates a new GTCM_GNP object and assigns it to the variable whose
> name is the contents of the $name variable.
>
> I don't see why this trickery with the variable name is being done.
> According to the documentation for eval, this should just be creating a
> local variable with this name -- a local variable which is returned at the
> end of this method. Therefore any arbitrary temporary variable name could
> have been used.
>
> Furthermore it is completely unclear to me why eval() is being used here.
> It doesn't appear to me to be necessary at all or to add anything of value.
>
> But there's no other place in the code you've shown where this variable
> gets promoted to a global. So perhaps this code actually makes a global
> variable, despite what the documentation says. If so, there's still no need
> for eval; you can just assign to $GLOBALS[$name] directly.
>
> In nodejs JavaScript, you wouldn't want to use globals at all; you could
> just define a private object in your module and store the objects in there
> as you make them.
>
> > if(!$$name)
> > {
> > $err_msg = "Cannot register, GTCM_GNP constructor failure.";
> > catch(throw(__FILE__, __LINE__, "register", 1, $err_msg));
> > return FALSE;
> > }
>
> If the new variable is empty, meaning the object could not be created, an
> error is thrown.
>
> > $this->m_cnt++;
>
> This counter is incremented, presumably a count of how many objects have
> been created.
>
> > $this->m_names[] = $name;
>
> The string $name is appended to the m_names array, as an indicator that
> this global variable now exists.
>
> > $this->m_rules[$name] = array($rule);
>
> The array of rules for $name is created with a single element: the regular
> expression $rule.
>
> > return $$name;
>
> The new object is returned.
>
> > }
>
> It's unclear why $GLOBALS or eval() were needed at all. It seems as though
> using a string-indexed array -- as was done for the m_rules array -- would
> have worked just as well. In JavaScript, this would be called an object
> instead of an array.
>
>
> > function lookUp($gvn_name)
> > {
> > foreach($this->m_rules as $name => $rule)
> > foreach($rule as $r)
> > if(ereg($r, $gvn_name))
> > return $name;
> > return null;
> > }
>
> This looks through all the rules for all the objects, and returns the name
> of the object that has a rule matching the $gvn_name variable. This uses
> the old deprecated ereg regular expression syntax: http://php.net/ereg ;
> Use of the newer PCRE regular expression syntax is recommended in PHP.
> JavaScript regular expressions are also PCRE-based.
>
>
> > /* Usage: $dir->unregister("db1"); */
> > function unregister($name)
> > {
> > if(!in_array($name, $this->m_names))
> > return;
> > $rule = $this->m_rules[$name];
> > $this->m_rules = array_diff($this->m_rules, array($rule));
> > $this->m_names = array_diff($this->m_names, array($name));
> > $this->m_cnt--;
> > }
>
> It looks like this removes all the rules associated with the $name object,
> and removes it from the m_names array and decrements the count of objects
> -- but does not actually delete the global variable containing the object
> itself.
>
>
> So it seems to be a bad / incomplete attempt at object orientation. What
> you really want is a single container to hold all your connections. Inside
> that container you'd have objects which contain each connection's
> connection object and its rules. Here's some code that seems to work, which
> I saved as connectionManager.js:
>
>
> var GTCM_GNP = require('./GTCM_GNP');
>
> var connections = {};
> var count = 0;
>
> exports.connect = function (name, rule, dat_file, server, port) {
> if (connections[name]) {
> connections[name].rules.push(rule);
> return connections[name].connection;
> }
> var newConnection = new GTCM_GNP(dat_file, server, port);
> count++;
> connections[name] = {
> connection: newConnection,
> rules: [rule]
> };
> return newConnection;
> };
>
> exports.lookUp = function (gvn_name) {
> var names = Object.keys(connections);
> for (var i = 0; i < count; i++) {
> var name = names[i];
> if (connections[name].rules.some(function(rule) {
> return rule.test(gvn_name);
> })) return name;
> }
> return null;
> };
>
> exports.unregister = function (name) {
> if (!connections[name]) return;
> delete connections[name];
> count--;
> };
>
>
> To test it out I made an index.js like this:
>
>
> var cm = require('./connectionManager.js');
>
> var conn1 = cm.connect('example', /hello/, 'foo.txt', 'localhost', 5555);
> var conn2 = cm.connect('example', /world/, 'foo.txt', 'localhost', 5555);
> var conn3 = cm.connect('something', /another/, 'bar.txt',
> '192.168.99.999', 6666);
>
> console.log(cm.lookUp("I say hello"));
> console.log(cm.lookUp("You say goodbye"));
> console.log(cm.lookUp('This is another one'));
>
> cm.unregister('example');
>
> console.log(cm.lookUp("I say hello"));
> console.log(cm.lookUp("You say goodbye"));
> console.log(cm.lookUp('This is another one'));
>
> cm.unregister('something');
>
> console.log(cm.lookUp("I say hello"));
> console.log(cm.lookUp("You say goodbye"));
> console.log(cm.lookUp('This is another one'));
>
>
> And a GTCM_GNP.js like this:
>
>
> function GTCM_GNP(dat_file, server, port) {
> this.dat_file = dat_file;
> this.server = server;
> this.port = port;
> console.log('made a new GTCM_GNP object, dat_file ' + dat_file + ',
> server ' + server + ', port ' + port);
> }
>
> module.exports = GTCM_GNP;
>
>
--
--
Job Board: http://jobs.nodejs.org/
Posting guidelines:
https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
You received this message because you are subscribed to the Google
Groups "nodejs" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/nodejs?hl=en?hl=en
---
You received this message because you are subscribed to the Google Groups
"nodejs" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/groups/opt_out.
