Re: Re: meaning or 'flags' in ZipArchive->open() ?

On Apr 9, 2015, at 4:15 PM, Maciek Sokolewicz wrote:

On 10 April 2015 at 00:59, Jeffry Killen <jekillen@prodigy.net> wrote: On Apr 9, 2015, at 3:41 PM, Maciek Sokolewicz wrote:

On 9-4-2015 21:48, Jeffry Killen wrote:

Hello; Is there a reference to explanations of the meanings of the flags here I have marked with ??: ZIPARCHIVE::OVERWRITE (I presume this means to remove existing

content

and start fresh) ZIPARCHIVE::CREATE ZIPARCHIVE::EXCL ?? (EXCL == exclude(?)) ZIPARCHIVE::CHECKCONS ?? There is no explanation in my copy of the manual accept what is obvious in the examples given. Thanks JK

Read the only up-to-date version of the manual: http://www.php.net/manual/en/zip.constants.php (and yes, they're class constants) - Tul

Thank you; very helpful. It would be nice if there was a full manual on using this alone. I could google using zip compression or something similar. So; as I understand it a constant will have an integer associated and might be used in a lookup array to get the string value? I will play around with this to get a feel for it. Thanks for time and attention JK Please reply to the list as well. The manual actually fully explains how to use them. It states that you need to supply one of the flags in various functions/methods to get some desired effect. For instance: http://www.php.net/manual/en/ziparchive.open.php When using ZipArchive::open() it requires up to 2 parameters: a filename, and an optional flag, which may be one of the following constants: ZipArchive::OVERWRITE, ZipArchive::CREATE, ZipArchive::EXCL or ZipArchive::CHECKCONS. Each constant has an integer value. What this value is exactly, you shouldn't care. Internally, the method wants to receive an integer; but for you (the developer), it's much easier to figure out what's going on by using a clear name; so instead you use a constant. So when the following is used: $filename = './archive.zip'; ZipArchive::open($filename, ZipArchive::CREATE); PHP translates it to: ZipArchive::open('./archive.zip', 1); // since the value of ZipArchive::CREATE is some number, for example 1 (I don't know for sure what it is, this is just for example purposes)

good guess... it is 1 according to my probing.

Now, you could of course just write things like: ZipArchive::open('./archive.zip', 1); ZipArchive::open('./archive.zip', 3); but do you now immediately know what's going on here? And what each flag does? Of course not. So instead we use constants which have a clear name that tells us what the flag means, and have the corresponding value (integer): ZipArchive::open('./archive.zip', ZipArchive::CREATE); ZipArchive::open('./archive.zip', ZipArchive::OVERWRITE); The manual itself shows you a ton of examples: http://www.php.net/manual/en/zip.examples.php and the entire ZipArchive chapter (http://www.php.net/manual/en/book.zip.php) also contains a ton of info. No need to google anything, just RTFM (online!). - Tul

OK: I thank you for pointers on where to find info in the manual on line. I have trouble navigating the manual to find these things myself. What I was wondering about most is the ZipArchive::CM... constants, Where are they important and how would one use them? for instance there is a ZipArchive constant CM_BZIP2: where and how would I specify this algorythm? And as well; comments, index, and name: What do these apply to? Or suppose I wanted to remove an element from a zip archive file without overwriting the whole thing? Is that possible? How would I do that? I am thinking along the lines of an O'Reilly or Apress text on the subject. That is what I would google for. I am in the process of compiling look up arrays to associate a string with each of the constant values I came across two oddities: mind you the version I am using is php v5.3.26 //ZipArchive::CM_REDUCE_4: also shows 5 $_constCM[5] = 'ZipArchive::CM_REDUCE_3: reduced with factor 3'; -1 won't fit into an indexed array: // ZipArchive::CM_DEFAULT gives -1: better of deflate or store $_constCM_DEF = array(); // CM ?? $_constCM_DEF['code'] = -1; $_constCM_DEF['means'] = "better of deflate or store"; I have just begun the ER constants. Additionally, this is the first time I have payed any attention to the inner workings of compression software. As always thanks for time and attention: JK