Not-clones that act like clones

[Rob]

Suppose I have a xxx.leo file in which I write multiple web pages (or other document types, same question).

• Each document is a separate @file (or @clean) external file.
• Inside each web page are sections (nodes with or without children) that all need to be the same content (perhaps some css or js stuff).
• I want all of the nodes to stay 'in sync' (change once, changes everywhere).
• I could easily do that with cloned nodes. However, we are strongly encouraged *not* to create cross-file clones.

Any suggestions on how to accomplish that without using clones?

I considered using the excellent leo-cloud plugin that Terry Brown wrote. However, I imagine that might not work as expected within the same xxx.leo file as each instance of the @leo-cloud node would be fighting against the others.

Thoughts and ideas welcome.

Rob...

[vitalije]

• I could easily do that with cloned nodes. However, we are strongly encouraged *not* to create cross-file clones.

Any suggestions on how to accomplish that without using clones?

As long as you are not using any other editor to edit those files and you are the only one who edits them, it is safe to use cross-file clones for this kind of problem.

If you do use other editors you might accidentally change the content of some parts that should be same in all other files. But that risk won't be any less even if you don't use clones. At least Leo will warn you if those sections ever get out of sync. Keeping same content in several files, and keeping it synchronized is not a trivial task. Leo with clones can help you to manage this task reasonably safe.

You might look for other mechanisms of sharing text parts between files, like including one file in all others, or extending templates, defining constants, ...

Perhaps you can create intermediate files with Leo/or other editors and then use some kind of pre-processor/script to put the section content in all the final files.

Vitalije

[Rob]

Thanks for clarifying, Vitalije. Yes, I'm the only one who would edit them and I don't use external editors, so clones would certainly be the easiest way to do that. I use \include{file.tex} for LaTeX documents, but don't know about a similar mechanism for html or css documents. Any of the other suggestions are way too complicated; especially compared to clones.

[vitalije]

For HTML and CSS there are a lot of pre-processors for example: pug for HTML and sass for css. Both of them have more than one way to define some section once and use it anywhere you like it. Basically you write source files in pug and sass format, and then compile those source files into the final HTML and CSS files. It requires some knowledge of new languages like pug and sass, but allows you to write much less source code for producing the same HTML and CSS.

Vitalije

[Rob]

Hmm, unfamiliar with those tools, will check them out. Thanks!

[Terry Brown]

On Sat, 9 Mar 2019 10:49:19 -0800 (PST)
vitalije <vita...@gmail.com> wrote:

> For HTML and CSS there are a lot of pre-processors for example: pug
> for HTML and sass for css. Both of them have more than one way to
> define some section once and use it anywhere you like it. Basically
> you write source files in pug and sass format, and then compile those
> source files into the final HTML and CSS files. It requires some
> knowledge of new languages like pug and sass, but allows you to write
> much less source code for producing the same HTML and CSS.

There's also the Jinja2 templating system which is written in / uses
Python. Bit of a learning curve but handy if you already know Python.
Used by the Django web app. stack. They don't use Jinja2 directly, but
the templating system is almost the identical so if you ever think you
might want to work with Django there's some pay off there.

I wouldn't recommend the leo-cloud plugin, it wasn't designed with
multiple instances in one file in mind.

Cheers -Terry

[Rob]

I have used html templates before in the context of CMS systems which already had the templating engines in place and would automatically replace the templates with the substitutions. However, that's not really what I need. I create html 'fragments' in Leo which are then copy/pasted into other online tools (such as an LMS or even a CMS) that typically have an html inline editor. I hate using the WYSIWYG editor, so I switch to source mode and paste the fragment copied from Leo. It works quite well, actually. In that scenario, these suggested  templating engines would require additional work to process to the output fragment. That's seriously overkill for what I'm doing.

[Edward K. Ream]

On Sat, Mar 9, 2019 at 11:00 AM Rob <lar...@gmail.com> wrote:

Suppose I have a xxx.leo file in which I write multiple web pages (or other document types, same question).

• Each document is a separate @file (or @clean) external file.
• Inside each web page are sections (nodes with or without children) that all need to be the same content (perhaps some css or js stuff).
• I want all of the nodes to stay 'in sync' (change once, changes everywhere).
• I could easily do that with cloned nodes. However, we are strongly encouraged *not* to create cross-file clones.

Imo, in your use case it's ok to use cross-file clones. The normal rules do not apply because html and css lack functions.  Try it and see what happens. If Leo can do the job there is less reason to use templates.

The reason that I recommend against cross-file clones is that there is no single "manager" or "owner" for the data.  But here the .leo file itself is the manager of the clones.  Just be sure only to change date from a single .leo file.  Then all should be well.

Edward

[Matt Wilkie]

As I understand it, using cross-file clones is somewhat safer if the clones are underneath @file/@clean nodes and not the @file nodes themselves. (I got myself into a pickle before by cloning @file nodes under different @path parents; don't remember the specifics now).

Matt

[Rob]

Thanks, Edward. However, I don't understand why it matters that html and css 'lack functions'.

Imo, in your use case it's ok to use cross-file clones. The normal rules do not apply because html and css lack functions.  

Thanks to everyone who 'weighed in' with comments; it appears that in my use case, that cross-file clones are the simplest, easiest way to accomplish my goal. Clones rock!

Rob...

[Edward K. Ream]

On Sun, Mar 10, 2019 at 7:18 PM Rob <lar...@gmail.com> wrote:

Thanks, Edward. However, I don't understand why it matters that html and css 'lack functions'.

You typically don't need clones if your language can define a function.  Just call the function.

Edward

[Rob]

Well, that certainly makes sense, thanks!

You typically don't need clones if your language can define a function.  Just call the function.

Edward

Now that I think of it that way, it reminds me that I do much the same thing w/ LaTeX commands (macros) for repeatable blocks of text.

Rob... 

[Edward K. Ream]

On Tue, Mar 12, 2019 at 2:55 PM Rob <lar...@gmail.com> wrote:

> Well, that certainly makes sense, thanks!

Glad to hear it.

> Now that I think of it that way, it reminds me that I do much the same thing w/ LaTeX commands (macros) for repeatable blocks of text.

Excellent.

Edward