Nominative objects of prepositions

Question

I've started noticing nominative complements of prepositions like 'según', 'salvo', and 'como'. It appears that there's only a small number of such prepositional trouble-makers, but I'm wondering how exceptional cases like these developed.

Me too!! Thanks for asking the question. :) - territurtle, Jul 13, 2011

Answer 1

I'm not sure if this is exactly what you're referring to but here's a bit on the subject

Prepositions

Exceptions:

• After the preposition ENTRE (between, among), yo,tú must be used instead of mí,ti: entre tú y yo (between you and me), entre nosotros (among us).
• After the preposition CON (with), the forms *con mí and *con ti are not correct. Instead they should be: conmigo (with me) and contigo (with you). These words come directly from Latin forms.
• Some fixed idiomatic expressions make exceptional use of prepositions (e.g. doubling): para conmigo (for me/myself [=para mí]), para contigo (for you/ yourself [=para ti]), de por mí (by me/myself), no significa nada de por sí (it doesn't mean anything by itself [sí -> reflexive pronoun, see later]).
• The preposition según (according to) carries its own stress and takes yo,tú afterwards (and not mí,ti). Admissible uses include: según tú, es correcto
  (according to you, it's correct), según dicen (according to what they say), -¿vendrás con nosotros? -según vea (-will you come with us? -depending on what I'll see [e.g. on future considerations]), etc.

Answer 2

The DRAE notes only two prepositions—entre and según—which are followed by the subject pronoun forms:

Por otra parte, debe tenerse en cuenta que la preposición entre y la preposición según (con el sentido de ‘en [mi, tu, su, etc.] opinión’) seleccionan las formas pronominales de sujeto, y no las de término de preposición:

«Lo que hablemos será entre tú y yo»

«En fin, que según tú, caso concluido»

Diccionario panhispánico de dudas ©2005
Real Academia Española © Todos los derechos reservados

The others which you mentioned, como and salvo, are used, respectively, in an adverbial and adjectival sense and are not classified as prepositions.

As far as recognizing usage patterns is concerned, the simple answer is that this comes as one grows more experienced with the language. The more you read and listen to native speakers, the more you will start to recognize such patterns and eventually, with enough exposure, you may even start to develop an intuitive "feel" for what sounds right.