Still with software science translations.. Now I'm coming to you with this expression that have always bothered me: "on the fly"

How the hood would you translate that *elegantly* to spanish?

It feels like "sobre la marcha" is way overkill, at least from a structure point of view. Also "al toque", sounds maybe too coloquial.

What do you think?

edit: so the english sentence could be:

> 
> The value is returned from a new function executed on the fly.
> 
> 
>
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No, I don’t like very much `sobre la marcha`. I mean, not always, and in “*software science translations*” almost never. I don’t feel it translate the whole idea exactly, with sometimes is: immediately and automatically, without user’s or external elements intervention. 

There are many other possibilities. 

My favorite is the simple direct translation: “`al vuelo`”.

Let’s see what the RAE said about “vuelo”:

> 
> al ~, o a ~.
> 
> 
> 1. locs. advs. Con prontitud.
> 
> 
> cazarlas alguien al ~.
> 
> 
> 1. loc. verb. Entender o notar con prontitud las cosas que no se dicen claramente o que se hacen ocultamente.
> 
> 
> coger al ~ algo.
> 
> 
> 1. loc. verb. Lograrlo de paso o casualmente.
> 
> 
> cogerlas alguien al ~.
> 
> 
> 1. loc. verb. coloq. cazarlas al vuelo.
> 
> 
> alzar el ~.
> 
> 
> 1. loc. verb. Echar a volar.
> 2. loc. verb. coloq. Marcharse de repente.
> 
> 
> 

I like this more than “`sobre la marcha`”, with the bonus that many people will automatically translate it to `on the fly` with the exact original meaning.

Some of the other possibilities are:

“sobre la marcha” (of course),

inmediátamente,

automáticamente, 

dinámicamente (this is probably my second favorite). *The windows layout change on the fly.* **El diseno de la pantalla cambia dinámicamente.** (a sort of this)

simultáneamente 

Let’s see some concrete examples:

[I have a class which calculates it's property on-the-fly, for example:](https://stackoverflow.com/q/15744634/1458030)

Tengo una clase que calcula sus propiedades al vuelo. (dinámicamente, en tiempo real)(I’m not sure how to correctly translate `class` and `properties`)

[An example enlightens the kerning-on-the-fly functionality:](https://stackoverflow.com/q/12654826/1458030)

Un ejemplo aclara esta funcionalidad de posicionamiento al vuelo. (dinámico, instantaneo, sobre la marcha)

[Encryption on the fly.](https://stackoverflow.com/q/16215990/1458030) 
Cifrado al vuelo. Cifrado simultaneo, en tiempo real, dinámico, automático…

On the fly translation. 
Traduccion simultanuea. (al vuelo, instantanea, sobre la marcha)

[More examples are here.](http://www.linguee.com/english-spanish?query=on%20the%20fly&source=english)
"Al toque" sounds to me like Latin America spanish... in Spain, al least in Madrid, we don't use that expression.

"On the fly" can be translated in several forms, but "sobre la marcha" I think is the most accurate. Other forms can be "al momento", "instantáneo" or "conforme se vea". Depends from context, but I think "sobre la marcha" is the most elegant, formal and easy.

Some examples:

> 
> We will fix the errors on the fly. - Iremos corrigiendo los errores
>  *sobre la marcha* / *conforme los veamos*.
> 
> 
> The system enables 'on-the-fly' processing of queries. - El sistema
>  permite el procesamiento *instantáneo* de consultas.
> 
> 
>