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Main Visitor ToString3 Non tail-recursive helper ToString3Help
package listFW.visitor; import listFW.*;public class ToString3 implements IListAlgo {public static final ToString3 Singleton = new ToString3();private ToString3() {} public Object emptyCase(IMTList host, Object... nu) { return "()";} public Object nonEmptyCase(INEList host, Object... nu) { return "(" + host.getFirst()+ host.getRest().execute( ToString3Help.Singleton);} } /** * Helps ToString3 compute the String* representation of the rest of the list. */class ToString3Help implements IListAlgo { public static final ToString3HelpSingleton = new ToString3Help(); private ToString3Help() {}public Object emptyCase( IMTList host, Object... nu) {return ")"; }public Object nonEmptyCase( INEList host, Object... nu) {return ", " + host.getFirst() + host.getRest().execute(this);} }

What makes each of the above different from one another is its helper visitor. Each helper defined in the above will only perform correctly if it is passed the appropriate parameter. In a sense, each helper is an implementation of the main visitor. We should hide each of them inside of its corresponding main visitor to ensure proper usage and achieve full encapsulation of the main visitor.

2. hiding helpers

The most secure way to hide the helper visitor is to move it inside of the main visitor and make it a private static class.

Hiding Named Helper Visitor inside of ToString1 Comments
package listFW.visitor; import listFW.*;public class ToString1WithHiddenHelper implements IListAlgo {public static final ToString1WithHiddenHelper Singleton = new ToString1WithHiddenHelper();private ToString1WithHiddenHelper() {} Singleton Pattern
private static class HiddenHelper implements IListAlgo {public static final HiddenHelper Singleton = new HiddenHelper();private HiddenHelper() {} public Object emptyCase(IMTList host,Object... acc) { return acc[0]+ ")"; }public Object nonEmptyCase(INEList host,Object... acc) { return host.getRest().execute(this,acc[0] + ", " + host.getFirst());} } The helper visitor has a name, HiddenHelper , and is defined privately and globally ( static ) inside of the main visitor ToString1WithHiddenHelper .
public Object emptyCase(IMTList host, Object... nu) {return "()"; }public Object nonEmptyCase(INEList host, Object... nu) {return host.getRest().execute( HiddenHelper.Singleton,"(" + host.getFirst()); }} The main visitor calls on its hidden helper singleton to help complete the job.
Hiding Named Helper Visitor inside of ToString2 Comments
package listFW.visitor; import listFW.*;public class ToString2WithHiddenHelper implements IListAlgo { public static finalToString2WithHiddenHelper Singleton = new ToString2WithHiddenHelper();private ToString2WithHiddenHelper() { }
private static class HiddenHelper implements IListAlgo { public static final HiddenHelper Singleton = new HiddenHelper();private HiddenHelper() { }public Object emptyCase(IMTList host, Object... acc) { return "(" + acc[0]+ ")"; }public Object nonEmptyCase(INEList host, Object... acc) { return host.getRest().execute(this,acc[0] + ", " + host.getFirst());} }
public Object emptyCase(IMTList host, Object... nu) { return "()";}public Object nonEmptyCase(INEList host, Object... nu) { return host.getRest().execute(HiddenHelper.Singleton,host.getFirst().toString()); }}

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Principles of object-oriented programming. OpenStax CNX. May 10, 2013 Download for free at http://legacy.cnx.org/content/col10213/1.37
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