deferred variable lookup in environment?

deferred variable lookup in environment?

[Ingo Hohmann]

Hi,

sorry if the subject is misleading, I'm not sure how to say it in few words.

I'm trying to have the date in a layer in an environment. In the text 
using the environment, I want to be able to set the date.
If the date is not set, the current date should be used, otherwise the 
set date.
This is what I've tried, but it is always the currentdate, that is 
displayes.

Environment file:

\def\mydate{}

\definelayer[firstpage]  % name of the layer
     [x=0mm, y=0mm,  % from upper left corner of paper
      width=\paperwidth, height=\paperheight] % let the layer cover the 
full paper

\setlayer[firstpage]    % name of the layer
     [hoffset=14cm, voffset=3.5cm]  % placement (from upper left corner 
of the layer)
     {\framed[frame=on, width=4cm, height=2cm]{

% always shows \currentdate
\doiftextelse{\mydate}{\mydate}{\currentdate}
}}

\setupbackgrounds[page][background={firstpage}]


File using this environment:

\environment[testenv]

\def\mydate{2011-11-11}

\starttext

% this shows the value from mydate
\doiftextelse{\mydate}{\mydate}{\currentdate}

\stoptext


Is it possible to get \mydate in the layer?


Kind regards,

Ingo


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Re: deferred variable lookup in environment?

[Marco Patzer]

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On 2013–02–02 Ingo Hohmann wrote:

> I'm trying to have the date in a layer in an environment. In the
> text using the environment, I want to be able to set the date.
> If the date is not set, the current date should be used, otherwise
> the set date.
> This is what I've tried, but it is always the currentdate, that is
> displayes.

You are trying to use the date before it is defined. You can use a
two-pass mechanism:

\define\mydate{\datasetvariable{mydata}{date}{date}}

\definelayer
  [firstpage]

\setlayer
  [firstpage]
  [hoffset=14cm, voffset=3.5cm]
  {\framed[frame=on, width=4cm, height=2cm]{%%
    \doiftextelse{\mydate}{\mydate}{\currentdate}}}

\setupbackgrounds
  [page]
  [background=firstpage]

\definedataset
  [mydata]

\setdataset
  [mydata]
  [date]
  [date=2011-11-11]

\starttext
  \doiftextelse{\mydate}{\mydate}{\currentdate}
\stoptext

Marco

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Re: deferred variable lookup in environment?

[Ingo Hohmann]

On 02/02/2013 12:31 AM, Marco Patzer wrote:
> On 2013–02–02 Ingo Hohmann wrote:
>
>> I'm trying to have the date in a layer in an environment. In the
>> text using the environment, I want to be able to set the date.
>> If the date is not set, the current date should be used, otherwise
>> the set date.
>> This is what I've tried, but it is always the currentdate, that is
>> displayes.
> You are trying to use the date before it is defined. You can use a
> two-pass mechanism:
>
> \define\mydate{\datasetvariable{mydata}{date}{date}}

Thank you Marco, this works.

Is it possible to update fields in the datasetvariables table, or is it 
only possible to replace the whole table?

\setdataset[data][info][date=\currentdate]
\setdataset[data][info][subject={subject}]

After the second line, the first value is gone.


Thank you,

Ingo


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___________________________________________________________________________________

Re: deferred variable lookup in environment?

[Marco Patzer]

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On 2013–02–05 Ingo Hohmann wrote:

> Is it possible to update fields in the datasetvariables table, or is
> it only possible to replace the whole table?

I don't know of an interface allowing that without directly dealing
with the Lua tables. Maybe you can use the tag for that:

> \setdataset[data][info][date=\currentdate]
> \setdataset[data][info][subject={subject}]

\setdataset[data][dateinfo]   [date=\currentdate]
\setdataset[data][subjectinfo][subject={subject}]


Marco

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